Re: [PATCH V2] mmc: core: Add host capability check for power class
On 2 April 2012 16:24, Subhash Jadavani subha...@codeaurora.org wrote:
-Original Message-
From: Saugata Das [mailto:saugata@linaro.org]
Sent: Monday, April 02, 2012 1:20 PM
To: Subhash Jadavani
Cc: Girish K S; linux-...@vger.kernel.org; patc...@linaro.org; linux-
samsung-...@vger.kernel.org; Chris Ball
Subject: Re: [PATCH V2] mmc: core: Add host capability check for power
class
On 28 March 2012 16:39, Subhash Jadavani subha...@codeaurora.org
wrote:
-Original Message-
From: linux-mmc-ow...@vger.kernel.org [mailto:linux-mmc-
ow...@vger.kernel.org] On Behalf Of Saugata Das
Sent: Thursday, December 15, 2011 6:35 PM
To: Girish K S
Cc: linux-...@vger.kernel.org; patc...@linaro.org; linux-samsung-
s...@vger.kernel.org; subha...@codeaurora.org; Chris Ball
Subject: Re: [PATCH V2] mmc: core: Add host capability check for
power
class
On 15 December 2011 16:22, Girish K S
girish.shivananja...@linaro.org
wrote:
On 15 December 2011 15:34, Saugata Das saugata@linaro.org
wrote:
On 15 December 2011 09:28, Girish K S
girish.shivananja...@linaro.org
wrote:
This patch adds a check whether the host supports maximum current
value obtained from the device's extended csd register for a
selected interface voltage and frequency.
cc: Chris Ball c...@laptop.org
Signed-off-by: Girish K S girish.shivananja...@linaro.org
---
Changes in v2:
deleted a unnecessary if else condition identified by
subhash J Changes in v1:
reduced the number of comparisons as per Hein's suggestion
drivers/mmc/core/mmc.c | 19 +++
include/linux/mmc/card.h | 4
2 files changed, 23 insertions(+), 0 deletions(-)
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index
006e932..b9ef777 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -688,6 +688,25 @@ static int mmc_select_powerclass(struct
mmc_card *card,
pwrclass_val = (pwrclass_val
EXT_CSD_PWR_CL_4BIT_MASK)
EXT_CSD_PWR_CL_4BIT_SHIFT;
+ if (pwrclass_val = MMC_MAX_CURRENT_800)
+ pwrclass_val = MMC_MAX_CURRENT_800;
+ else if (pwrclass_val = MMC_MAX_CURRENT_600)
+ pwrclass_val = MMC_MAX_CURRENT_600;
+ else if (pwrclass_val = MMC_MAX_CURRENT_400)
+ pwrclass_val = MMC_MAX_CURRENT_400;
+ else
+ pwrclass_val = MMC_MAX_CURRENT_200;
+
+ if ((pwrclass_val == MMC_MAX_CURRENT_800)
+ !(card-host-caps MMC_CAP_MAX_CURRENT_800))
+ pwrclass_val = MMC_MAX_CURRENT_600;
+ if ((pwrclass_val == MMC_MAX_CURRENT_600)
+ !(card-host-caps MMC_CAP_MAX_CURRENT_600))
+ pwrclass_val = MMC_MAX_CURRENT_400;
+ if ((pwrclass_val == MMC_MAX_CURRENT_400)
+ !(card-host-caps MMC_CAP_MAX_CURRENT_400))
+ pwrclass_val = MMC_MAX_CURRENT_200;
+
/* If the power class is different from the default value
*/
if (pwrclass_val 0) {
err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
It is not allowed to set the POWER_CLASS with any value other than
what is mentioned in the PWR_CL_ff_vvv or PWR_CL_DDR_ff_vvv for
the
corresponding frequency, voltage. That is, if PWR_CL_200_195 is 14
and we want to operate at HS200 then the only value allowed for
POWER_CLASS is 14. So, we need to check the PWR_CL numbers and
choose
the operating mode (HS200/DDR50/..) based on the platform
capability to support the current consumption and set the
corresponding POWER_CLASS value.
Please refer to section 6.6.5 of the 4.5 spec.
The upstreamed code reads the extended csd value based on the
already set voltage level and frequency of host. So it will get the
required power class value which can be set directly. Is my
understanding correct?
It is not enough to just check the voltage level and frequency.
Consider this example, host has capability to support
MMC_CAP_MAX_CURRENT_400, the PWR_CL_DDR_52_360 has the value
9
(400mA) and PWR_CL_200_360 has the value 14 (800mA). Then even
though
the host might be capable to run 200MHz clock and 3.6V, it can only
enable DDR at 52MHz and set 9 in POWER_CLASS.
I think, in mmc_select_powerclass, we need to loop through the power
classes of all supported modes of transfer (HS200, DDR52, ... ) and
choose
the
mode which gives maximum bandwidth but falls within host capability
of current consumption. Then set this to POWER_CLASS byte and also
use the same information when setting HS_TIMING in mmc_init_card.
Hi Saugata,
Does the spec mandates you to set the power class to what is needed by
frequency/voltage combination? I can't see that mentioned anywhere
explicitly in eMMC4.5 spec (if it is mentioned in spec, please
Re: [PATCH V2] mmc: core: Add host capability check for power class
On 28 March 2012 16:39, Subhash Jadavani subha...@codeaurora.org wrote:
-Original Message-
From: linux-mmc-ow...@vger.kernel.org [mailto:linux-mmc-
ow...@vger.kernel.org] On Behalf Of Saugata Das
Sent: Thursday, December 15, 2011 6:35 PM
To: Girish K S
Cc: linux-...@vger.kernel.org; patc...@linaro.org; linux-samsung-
s...@vger.kernel.org; subha...@codeaurora.org; Chris Ball
Subject: Re: [PATCH V2] mmc: core: Add host capability check for power
class
On 15 December 2011 16:22, Girish K S girish.shivananja...@linaro.org
wrote:
On 15 December 2011 15:34, Saugata Das saugata@linaro.org wrote:
On 15 December 2011 09:28, Girish K S girish.shivananja...@linaro.org
wrote:
This patch adds a check whether the host supports maximum current
value obtained from the device's extended csd register for a
selected interface voltage and frequency.
cc: Chris Ball c...@laptop.org
Signed-off-by: Girish K S girish.shivananja...@linaro.org
---
Changes in v2:
deleted a unnecessary if else condition identified by subhash
J Changes in v1:
reduced the number of comparisons as per Hein's suggestion
drivers/mmc/core/mmc.c | 19 +++
include/linux/mmc/card.h | 4
2 files changed, 23 insertions(+), 0 deletions(-)
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c index
006e932..b9ef777 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -688,6 +688,25 @@ static int mmc_select_powerclass(struct
mmc_card *card,
pwrclass_val = (pwrclass_val
EXT_CSD_PWR_CL_4BIT_MASK)
EXT_CSD_PWR_CL_4BIT_SHIFT;
+ if (pwrclass_val = MMC_MAX_CURRENT_800)
+ pwrclass_val = MMC_MAX_CURRENT_800;
+ else if (pwrclass_val = MMC_MAX_CURRENT_600)
+ pwrclass_val = MMC_MAX_CURRENT_600;
+ else if (pwrclass_val = MMC_MAX_CURRENT_400)
+ pwrclass_val = MMC_MAX_CURRENT_400;
+ else
+ pwrclass_val = MMC_MAX_CURRENT_200;
+
+ if ((pwrclass_val == MMC_MAX_CURRENT_800)
+ !(card-host-caps MMC_CAP_MAX_CURRENT_800))
+ pwrclass_val = MMC_MAX_CURRENT_600;
+ if ((pwrclass_val == MMC_MAX_CURRENT_600)
+ !(card-host-caps MMC_CAP_MAX_CURRENT_600))
+ pwrclass_val = MMC_MAX_CURRENT_400;
+ if ((pwrclass_val == MMC_MAX_CURRENT_400)
+ !(card-host-caps MMC_CAP_MAX_CURRENT_400))
+ pwrclass_val = MMC_MAX_CURRENT_200;
+
/* If the power class is different from the default value */
if (pwrclass_val 0) {
err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
It is not allowed to set the POWER_CLASS with any value other than
what is mentioned in the PWR_CL_ff_vvv or PWR_CL_DDR_ff_vvv for
the
corresponding frequency, voltage. That is, if PWR_CL_200_195 is 14
and we want to operate at HS200 then the only value allowed for
POWER_CLASS is 14. So, we need to check the PWR_CL numbers and
choose
the operating mode (HS200/DDR50/..) based on the platform capability
to support the current consumption and set the corresponding
POWER_CLASS value.
Please refer to section 6.6.5 of the 4.5 spec.
The upstreamed code reads the extended csd value based on the already
set voltage level and frequency of host. So it will get the required
power class value which can be set directly. Is my understanding
correct?
It is not enough to just check the voltage level and frequency.
Consider this example, host has capability to support
MMC_CAP_MAX_CURRENT_400, the PWR_CL_DDR_52_360 has the value 9
(400mA) and PWR_CL_200_360 has the value 14 (800mA). Then even though
the host might be capable to run 200MHz clock and 3.6V, it can only enable
DDR at 52MHz and set 9 in POWER_CLASS.
I think, in mmc_select_powerclass, we need to loop through the power
classes of all supported modes of transfer (HS200, DDR52, ... ) and choose
the
mode which gives maximum bandwidth but falls within host capability of
current consumption. Then set this to POWER_CLASS byte and also use the
same information when setting HS_TIMING in mmc_init_card.
Hi Saugata,
Does the spec mandates you to set the power class to what is needed by
frequency/voltage combination? I can't see that mentioned anywhere
explicitly in eMMC4.5 spec (if it is mentioned in spec, please let me know
section and line number). It may be still possible to set the power class
lower than what is needed by frequency/voltage combination. Say for example,
8-bit HS200 (200MHz) with high voltage cards may specify power class
(PWR_CL_200_3_6) value of 14 (800 mA) but that doesn't mean if you want the
card to work in 8-bit HS200 mode, its POWER_CLASS value must be 14 (800mA).
If host's VDD regulator is only capable of say 600mA then it may still set
the POWER_CLASS to 12 (600 mA) which should be the indication
RE: [PATCH V2] mmc: core: Add host capability check for power class
-Original Message-
From: Saugata Das [mailto:saugata@linaro.org]
Sent: Monday, April 02, 2012 1:20 PM
To: Subhash Jadavani
Cc: Girish K S; linux-...@vger.kernel.org; patc...@linaro.org; linux-
samsung-...@vger.kernel.org; Chris Ball
Subject: Re: [PATCH V2] mmc: core: Add host capability check for power
class
On 28 March 2012 16:39, Subhash Jadavani subha...@codeaurora.org
wrote:
-Original Message-
From: linux-mmc-ow...@vger.kernel.org [mailto:linux-mmc-
ow...@vger.kernel.org] On Behalf Of Saugata Das
Sent: Thursday, December 15, 2011 6:35 PM
To: Girish K S
Cc: linux-...@vger.kernel.org; patc...@linaro.org; linux-samsung-
s...@vger.kernel.org; subha...@codeaurora.org; Chris Ball
Subject: Re: [PATCH V2] mmc: core: Add host capability check for
power
class
On 15 December 2011 16:22, Girish K S
girish.shivananja...@linaro.org
wrote:
On 15 December 2011 15:34, Saugata Das saugata@linaro.org
wrote:
On 15 December 2011 09:28, Girish K S
girish.shivananja...@linaro.org
wrote:
This patch adds a check whether the host supports maximum current
value obtained from the device's extended csd register for a
selected interface voltage and frequency.
cc: Chris Ball c...@laptop.org
Signed-off-by: Girish K S girish.shivananja...@linaro.org
---
Changes in v2:
deleted a unnecessary if else condition identified by
subhash J Changes in v1:
reduced the number of comparisons as per Hein's suggestion
drivers/mmc/core/mmc.c | 19 +++
include/linux/mmc/card.h | 4
2 files changed, 23 insertions(+), 0 deletions(-)
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index
006e932..b9ef777 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -688,6 +688,25 @@ static int mmc_select_powerclass(struct
mmc_card *card,
pwrclass_val = (pwrclass_val
EXT_CSD_PWR_CL_4BIT_MASK)
EXT_CSD_PWR_CL_4BIT_SHIFT;
+ if (pwrclass_val = MMC_MAX_CURRENT_800)
+ pwrclass_val = MMC_MAX_CURRENT_800;
+ else if (pwrclass_val = MMC_MAX_CURRENT_600)
+ pwrclass_val = MMC_MAX_CURRENT_600;
+ else if (pwrclass_val = MMC_MAX_CURRENT_400)
+ pwrclass_val = MMC_MAX_CURRENT_400;
+ else
+ pwrclass_val = MMC_MAX_CURRENT_200;
+
+ if ((pwrclass_val == MMC_MAX_CURRENT_800)
+ !(card-host-caps MMC_CAP_MAX_CURRENT_800))
+ pwrclass_val = MMC_MAX_CURRENT_600;
+ if ((pwrclass_val == MMC_MAX_CURRENT_600)
+ !(card-host-caps MMC_CAP_MAX_CURRENT_600))
+ pwrclass_val = MMC_MAX_CURRENT_400;
+ if ((pwrclass_val == MMC_MAX_CURRENT_400)
+ !(card-host-caps MMC_CAP_MAX_CURRENT_400))
+ pwrclass_val = MMC_MAX_CURRENT_200;
+
/* If the power class is different from the default value
*/
if (pwrclass_val 0) {
err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
It is not allowed to set the POWER_CLASS with any value other than
what is mentioned in the PWR_CL_ff_vvv or PWR_CL_DDR_ff_vvv for
the
corresponding frequency, voltage. That is, if PWR_CL_200_195 is 14
and we want to operate at HS200 then the only value allowed for
POWER_CLASS is 14. So, we need to check the PWR_CL numbers and
choose
the operating mode (HS200/DDR50/..) based on the platform
capability to support the current consumption and set the
corresponding POWER_CLASS value.
Please refer to section 6.6.5 of the 4.5 spec.
The upstreamed code reads the extended csd value based on the
already set voltage level and frequency of host. So it will get the
required power class value which can be set directly. Is my
understanding correct?
It is not enough to just check the voltage level and frequency.
Consider this example, host has capability to support
MMC_CAP_MAX_CURRENT_400, the PWR_CL_DDR_52_360 has the value
9
(400mA) and PWR_CL_200_360 has the value 14 (800mA). Then even
though
the host might be capable to run 200MHz clock and 3.6V, it can only
enable DDR at 52MHz and set 9 in POWER_CLASS.
I think, in mmc_select_powerclass, we need to loop through the power
classes of all supported modes of transfer (HS200, DDR52, ... ) and
choose
the
mode which gives maximum bandwidth but falls within host capability
of current consumption. Then set this to POWER_CLASS byte and also
use the same information when setting HS_TIMING in mmc_init_card.
Hi Saugata,
Does the spec mandates you to set the power class to what is needed by
frequency/voltage combination? I can't see that mentioned anywhere
explicitly in eMMC4.5 spec (if it is mentioned in spec, please let me
know section and line number). It may be still possible
Re: [PATCH V2] mmc: core: Add host capability check for power class
On 29 March 2012 11:17, Girish K S girish.shivananja...@linaro.org wrote:
On 28 March 2012 16:39, Subhash Jadavani subha...@codeaurora.org wrote:
-Original Message-
From: linux-mmc-ow...@vger.kernel.org [mailto:linux-mmc-
ow...@vger.kernel.org] On Behalf Of Saugata Das
Sent: Thursday, December 15, 2011 6:35 PM
To: Girish K S
Cc: linux-...@vger.kernel.org; patc...@linaro.org; linux-samsung-
s...@vger.kernel.org; subha...@codeaurora.org; Chris Ball
Subject: Re: [PATCH V2] mmc: core: Add host capability check for power
class
On 15 December 2011 16:22, Girish K S girish.shivananja...@linaro.org
wrote:
On 15 December 2011 15:34, Saugata Das saugata@linaro.org wrote:
On 15 December 2011 09:28, Girish K S girish.shivananja...@linaro.org
wrote:
This patch adds a check whether the host supports maximum current
value obtained from the device's extended csd register for a
selected interface voltage and frequency.
cc: Chris Ball c...@laptop.org
Signed-off-by: Girish K S girish.shivananja...@linaro.org
---
Changes in v2:
deleted a unnecessary if else condition identified by subhash
J Changes in v1:
reduced the number of comparisons as per Hein's suggestion
drivers/mmc/core/mmc.c | 19 +++
include/linux/mmc/card.h | 4
2 files changed, 23 insertions(+), 0 deletions(-)
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c index
006e932..b9ef777 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -688,6 +688,25 @@ static int mmc_select_powerclass(struct
mmc_card *card,
pwrclass_val = (pwrclass_val
EXT_CSD_PWR_CL_4BIT_MASK)
EXT_CSD_PWR_CL_4BIT_SHIFT;
+ if (pwrclass_val = MMC_MAX_CURRENT_800)
+ pwrclass_val = MMC_MAX_CURRENT_800;
+ else if (pwrclass_val = MMC_MAX_CURRENT_600)
+ pwrclass_val = MMC_MAX_CURRENT_600;
+ else if (pwrclass_val = MMC_MAX_CURRENT_400)
+ pwrclass_val = MMC_MAX_CURRENT_400;
+ else
+ pwrclass_val = MMC_MAX_CURRENT_200;
+
+ if ((pwrclass_val == MMC_MAX_CURRENT_800)
+ !(card-host-caps MMC_CAP_MAX_CURRENT_800))
+ pwrclass_val = MMC_MAX_CURRENT_600;
+ if ((pwrclass_val == MMC_MAX_CURRENT_600)
+ !(card-host-caps MMC_CAP_MAX_CURRENT_600))
+ pwrclass_val = MMC_MAX_CURRENT_400;
+ if ((pwrclass_val == MMC_MAX_CURRENT_400)
+ !(card-host-caps MMC_CAP_MAX_CURRENT_400))
+ pwrclass_val = MMC_MAX_CURRENT_200;
+
/* If the power class is different from the default value */
if (pwrclass_val 0) {
err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
It is not allowed to set the POWER_CLASS with any value other than
what is mentioned in the PWR_CL_ff_vvv or PWR_CL_DDR_ff_vvv for
the
corresponding frequency, voltage. That is, if PWR_CL_200_195 is 14
and we want to operate at HS200 then the only value allowed for
POWER_CLASS is 14. So, we need to check the PWR_CL numbers and
choose
the operating mode (HS200/DDR50/..) based on the platform capability
to support the current consumption and set the corresponding
POWER_CLASS value.
Please refer to section 6.6.5 of the 4.5 spec.
The upstreamed code reads the extended csd value based on the already
set voltage level and frequency of host. So it will get the required
power class value which can be set directly. Is my understanding
correct?
It is not enough to just check the voltage level and frequency.
Consider this example, host has capability to support
MMC_CAP_MAX_CURRENT_400, the PWR_CL_DDR_52_360 has the value 9
(400mA) and PWR_CL_200_360 has the value 14 (800mA). Then even though
the host might be capable to run 200MHz clock and 3.6V, it can only enable
DDR at 52MHz and set 9 in POWER_CLASS.
I think, in mmc_select_powerclass, we need to loop through the power
classes of all supported modes of transfer (HS200, DDR52, ... ) and choose
the
mode which gives maximum bandwidth but falls within host capability of
current consumption. Then set this to POWER_CLASS byte and also use the
same information when setting HS_TIMING in mmc_init_card.
Hi Saugata,
Does the spec mandates you to set the power class to what is needed by
frequency/voltage combination? I can't see that mentioned anywhere
explicitly in eMMC4.5 spec (if it is mentioned in spec, please let me know
section and line number). It may be still possible to set the power class
lower than what is needed by frequency/voltage combination. Say for example,
8-bit HS200 (200MHz) with high voltage cards may specify power class
(PWR_CL_200_3_6) value of 14 (800 mA) but that doesn't mean if you want the
card to work in 8-bit HS200 mode, its POWER_CLASS value must be 14 (800mA).
If host's VDD regulator is only capable of say 600mA
RE: [PATCH V2] mmc: core: Add host capability check for power class
-Original Message-
From: linux-mmc-ow...@vger.kernel.org [mailto:linux-mmc-
ow...@vger.kernel.org] On Behalf Of Girish K S
Sent: Friday, March 30, 2012 10:29 AM
To: Subhash Jadavani
Cc: Saugata Das; linux-...@vger.kernel.org; patc...@linaro.org; linux-
samsung-...@vger.kernel.org; Chris Ball
Subject: Re: [PATCH V2] mmc: core: Add host capability check for power
class
On 29 March 2012 11:17, Girish K S girish.shivananja...@linaro.org
wrote:
On 28 March 2012 16:39, Subhash Jadavani subha...@codeaurora.org
wrote:
-Original Message-
From: linux-mmc-ow...@vger.kernel.org [mailto:linux-mmc-
ow...@vger.kernel.org] On Behalf Of Saugata Das
Sent: Thursday, December 15, 2011 6:35 PM
To: Girish K S
Cc: linux-...@vger.kernel.org; patc...@linaro.org; linux-samsung-
s...@vger.kernel.org; subha...@codeaurora.org; Chris Ball
Subject: Re: [PATCH V2] mmc: core: Add host capability check for
power
class
On 15 December 2011 16:22, Girish K S
girish.shivananja...@linaro.org
wrote:
On 15 December 2011 15:34, Saugata Das saugata@linaro.org
wrote:
On 15 December 2011 09:28, Girish K S
girish.shivananja...@linaro.org
wrote:
This patch adds a check whether the host supports maximum
current value obtained from the device's extended csd register
for a selected interface voltage and frequency.
cc: Chris Ball c...@laptop.org
Signed-off-by: Girish K S girish.shivananja...@linaro.org
---
Changes in v2:
deleted a unnecessary if else condition identified by
subhash J Changes in v1:
reduced the number of comparisons as per Hein's suggestion
drivers/mmc/core/mmc.c | 19 +++
include/linux/mmc/card.h | 4
2 files changed, 23 insertions(+), 0 deletions(-)
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index
006e932..b9ef777 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -688,6 +688,25 @@ static int mmc_select_powerclass(struct
mmc_card *card,
pwrclass_val = (pwrclass_val
EXT_CSD_PWR_CL_4BIT_MASK)
EXT_CSD_PWR_CL_4BIT_SHIFT;
+ if (pwrclass_val = MMC_MAX_CURRENT_800)
+ pwrclass_val = MMC_MAX_CURRENT_800;
+ else if (pwrclass_val = MMC_MAX_CURRENT_600)
+ pwrclass_val = MMC_MAX_CURRENT_600;
+ else if (pwrclass_val = MMC_MAX_CURRENT_400)
+ pwrclass_val = MMC_MAX_CURRENT_400;
+ else
+ pwrclass_val = MMC_MAX_CURRENT_200;
+
+ if ((pwrclass_val == MMC_MAX_CURRENT_800)
+ !(card-host-caps MMC_CAP_MAX_CURRENT_800))
+ pwrclass_val = MMC_MAX_CURRENT_600;
+ if ((pwrclass_val == MMC_MAX_CURRENT_600)
+ !(card-host-caps MMC_CAP_MAX_CURRENT_600))
+ pwrclass_val = MMC_MAX_CURRENT_400;
+ if ((pwrclass_val == MMC_MAX_CURRENT_400)
+ !(card-host-caps MMC_CAP_MAX_CURRENT_400))
+ pwrclass_val = MMC_MAX_CURRENT_200;
+
/* If the power class is different from the default value
*/
if (pwrclass_val 0) {
err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
It is not allowed to set the POWER_CLASS with any value other
than what is mentioned in the PWR_CL_ff_vvv or
PWR_CL_DDR_ff_vvv
for
the
corresponding frequency, voltage. That is, if PWR_CL_200_195 is
14 and we want to operate at HS200 then the only value allowed
for POWER_CLASS is 14. So, we need to check the PWR_CL numbers
and
choose
the operating mode (HS200/DDR50/..) based on the platform
capability to support the current consumption and set the
corresponding POWER_CLASS value.
Please refer to section 6.6.5 of the 4.5 spec.
The upstreamed code reads the extended csd value based on the
already set voltage level and frequency of host. So it will get
the required power class value which can be set directly. Is my
understanding correct?
It is not enough to just check the voltage level and frequency.
Consider this example, host has capability to support
MMC_CAP_MAX_CURRENT_400, the PWR_CL_DDR_52_360 has the
value 9
(400mA) and PWR_CL_200_360 has the value 14 (800mA). Then even
though the host might be capable to run 200MHz clock and 3.6V, it
can only enable DDR at 52MHz and set 9 in POWER_CLASS.
I think, in mmc_select_powerclass, we need to loop through the power
classes of all supported modes of transfer (HS200, DDR52, ... ) and
choose
the
mode which gives maximum bandwidth but falls within host capability
of current consumption. Then set this to POWER_CLASS byte and also
use the same information when setting HS_TIMING in mmc_init_card.
Hi Saugata,
Does the spec mandates you to set the power class to what is needed
by frequency/voltage combination? I can't see that mentioned
Re: [PATCH V2] mmc: core: Add host capability check for power class
On 28 March 2012 16:39, Subhash Jadavani subha...@codeaurora.org wrote:
-Original Message-
From: linux-mmc-ow...@vger.kernel.org [mailto:linux-mmc-
ow...@vger.kernel.org] On Behalf Of Saugata Das
Sent: Thursday, December 15, 2011 6:35 PM
To: Girish K S
Cc: linux-...@vger.kernel.org; patc...@linaro.org; linux-samsung-
s...@vger.kernel.org; subha...@codeaurora.org; Chris Ball
Subject: Re: [PATCH V2] mmc: core: Add host capability check for power
class
On 15 December 2011 16:22, Girish K S girish.shivananja...@linaro.org
wrote:
On 15 December 2011 15:34, Saugata Das saugata@linaro.org wrote:
On 15 December 2011 09:28, Girish K S girish.shivananja...@linaro.org
wrote:
This patch adds a check whether the host supports maximum current
value obtained from the device's extended csd register for a
selected interface voltage and frequency.
cc: Chris Ball c...@laptop.org
Signed-off-by: Girish K S girish.shivananja...@linaro.org
---
Changes in v2:
deleted a unnecessary if else condition identified by subhash
J Changes in v1:
reduced the number of comparisons as per Hein's suggestion
drivers/mmc/core/mmc.c | 19 +++
include/linux/mmc/card.h | 4
2 files changed, 23 insertions(+), 0 deletions(-)
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c index
006e932..b9ef777 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -688,6 +688,25 @@ static int mmc_select_powerclass(struct
mmc_card *card,
pwrclass_val = (pwrclass_val
EXT_CSD_PWR_CL_4BIT_MASK)
EXT_CSD_PWR_CL_4BIT_SHIFT;
+ if (pwrclass_val = MMC_MAX_CURRENT_800)
+ pwrclass_val = MMC_MAX_CURRENT_800;
+ else if (pwrclass_val = MMC_MAX_CURRENT_600)
+ pwrclass_val = MMC_MAX_CURRENT_600;
+ else if (pwrclass_val = MMC_MAX_CURRENT_400)
+ pwrclass_val = MMC_MAX_CURRENT_400;
+ else
+ pwrclass_val = MMC_MAX_CURRENT_200;
+
+ if ((pwrclass_val == MMC_MAX_CURRENT_800)
+ !(card-host-caps MMC_CAP_MAX_CURRENT_800))
+ pwrclass_val = MMC_MAX_CURRENT_600;
+ if ((pwrclass_val == MMC_MAX_CURRENT_600)
+ !(card-host-caps MMC_CAP_MAX_CURRENT_600))
+ pwrclass_val = MMC_MAX_CURRENT_400;
+ if ((pwrclass_val == MMC_MAX_CURRENT_400)
+ !(card-host-caps MMC_CAP_MAX_CURRENT_400))
+ pwrclass_val = MMC_MAX_CURRENT_200;
+
/* If the power class is different from the default value */
if (pwrclass_val 0) {
err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
It is not allowed to set the POWER_CLASS with any value other than
what is mentioned in the PWR_CL_ff_vvv or PWR_CL_DDR_ff_vvv for
the
corresponding frequency, voltage. That is, if PWR_CL_200_195 is 14
and we want to operate at HS200 then the only value allowed for
POWER_CLASS is 14. So, we need to check the PWR_CL numbers and
choose
the operating mode (HS200/DDR50/..) based on the platform capability
to support the current consumption and set the corresponding
POWER_CLASS value.
Please refer to section 6.6.5 of the 4.5 spec.
The upstreamed code reads the extended csd value based on the already
set voltage level and frequency of host. So it will get the required
power class value which can be set directly. Is my understanding
correct?
It is not enough to just check the voltage level and frequency.
Consider this example, host has capability to support
MMC_CAP_MAX_CURRENT_400, the PWR_CL_DDR_52_360 has the value 9
(400mA) and PWR_CL_200_360 has the value 14 (800mA). Then even though
the host might be capable to run 200MHz clock and 3.6V, it can only enable
DDR at 52MHz and set 9 in POWER_CLASS.
I think, in mmc_select_powerclass, we need to loop through the power
classes of all supported modes of transfer (HS200, DDR52, ... ) and choose
the
mode which gives maximum bandwidth but falls within host capability of
current consumption. Then set this to POWER_CLASS byte and also use the
same information when setting HS_TIMING in mmc_init_card.
Hi Saugata,
Does the spec mandates you to set the power class to what is needed by
frequency/voltage combination? I can't see that mentioned anywhere
explicitly in eMMC4.5 spec (if it is mentioned in spec, please let me know
section and line number). It may be still possible to set the power class
lower than what is needed by frequency/voltage combination. Say for example,
8-bit HS200 (200MHz) with high voltage cards may specify power class
(PWR_CL_200_3_6) value of 14 (800 mA) but that doesn't mean if you want the
card to work in 8-bit HS200 mode, its POWER_CLASS value must be 14 (800mA).
If host's VDD regulator is only capable of say 600mA then it may still set
the POWER_CLASS to 12 (600 mA) which should be the indication
Re: [PATCH V2] mmc: core: Add host capability check for power class
On 15 December 2011 16:22, Girish K S girish.shivananja...@linaro.org wrote:
On 15 December 2011 15:34, Saugata Das saugata@linaro.org wrote:
On 15 December 2011 09:28, Girish K S girish.shivananja...@linaro.org
wrote:
This patch adds a check whether the host supports maximum current value
obtained from the device's extended csd register for a selected interface
voltage and frequency.
cc: Chris Ball c...@laptop.org
Signed-off-by: Girish K S girish.shivananja...@linaro.org
---
Changes in v2:
deleted a unnecessary if else condition identified by subhash J
Changes in v1:
reduced the number of comparisons as per Hein's suggestion
drivers/mmc/core/mmc.c | 19 +++
include/linux/mmc/card.h | 4
2 files changed, 23 insertions(+), 0 deletions(-)
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 006e932..b9ef777 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -688,6 +688,25 @@ static int mmc_select_powerclass(struct mmc_card *card,
pwrclass_val = (pwrclass_val EXT_CSD_PWR_CL_4BIT_MASK)
EXT_CSD_PWR_CL_4BIT_SHIFT;
+ if (pwrclass_val = MMC_MAX_CURRENT_800)
+ pwrclass_val = MMC_MAX_CURRENT_800;
+ else if (pwrclass_val = MMC_MAX_CURRENT_600)
+ pwrclass_val = MMC_MAX_CURRENT_600;
+ else if (pwrclass_val = MMC_MAX_CURRENT_400)
+ pwrclass_val = MMC_MAX_CURRENT_400;
+ else
+ pwrclass_val = MMC_MAX_CURRENT_200;
+
+ if ((pwrclass_val == MMC_MAX_CURRENT_800)
+ !(card-host-caps MMC_CAP_MAX_CURRENT_800))
+ pwrclass_val = MMC_MAX_CURRENT_600;
+ if ((pwrclass_val == MMC_MAX_CURRENT_600)
+ !(card-host-caps MMC_CAP_MAX_CURRENT_600))
+ pwrclass_val = MMC_MAX_CURRENT_400;
+ if ((pwrclass_val == MMC_MAX_CURRENT_400)
+ !(card-host-caps MMC_CAP_MAX_CURRENT_400))
+ pwrclass_val = MMC_MAX_CURRENT_200;
+
/* If the power class is different from the default value */
if (pwrclass_val 0) {
err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
It is not allowed to set the POWER_CLASS with any value other than
what is mentioned in the PWR_CL_ff_vvv or PWR_CL_DDR_ff_vvv for the
corresponding frequency, voltage. That is, if PWR_CL_200_195 is 14 and
we want to operate at HS200 then the only value allowed for
POWER_CLASS is 14. So, we need to check the PWR_CL numbers and choose
the operating mode (HS200/DDR50/..) based on the platform capability
to support the current consumption and set the corresponding
POWER_CLASS value.
Please refer to section 6.6.5 of the 4.5 spec.
The upstreamed code reads the extended csd value based on the already
set voltage level and frequency of host. So it will get the required
power class value which can be set directly. Is my understanding
correct?
It is not enough to just check the voltage level and frequency.
Consider this example, host has capability to support
MMC_CAP_MAX_CURRENT_400, the PWR_CL_DDR_52_360 has the value 9 (400mA)
and PWR_CL_200_360 has the value 14 (800mA). Then even though the host
might be capable to run 200MHz clock and 3.6V, it can only enable DDR
at 52MHz and set 9 in POWER_CLASS.
I think, in mmc_select_powerclass, we need to loop through the power
classes of all supported modes of transfer (HS200, DDR52, ... ) and
choose the mode which gives maximum bandwidth but falls within host
capability of current consumption. Then set this to POWER_CLASS byte
and also use the same information when setting HS_TIMING in
mmc_init_card.
diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index 9478a6b..c5e031a 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -195,6 +195,10 @@ struct mmc_part {
#define MMC_BLK_DATA_AREA_GP (12)
};
+#define MMC_MAX_CURRENT_200 (0)
+#define MMC_MAX_CURRENT_400 (7)
+#define MMC_MAX_CURRENT_600 (11)
+#define MMC_MAX_CURRENT_800 (13)
/*
* MMC device
*/
--
1.7.1
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Re: [PATCH V2] mmc: core: Add host capability check for power class
On 15 December 2011 11:33, amit kachhap amit.kach...@linaro.org wrote:
On Thu, Dec 15, 2011 at 9:28 AM, Girish K S
girish.shivananja...@linaro.org wrote:
This patch adds a check whether the host supports maximum current value
obtained from the device's extended csd register for a selected interface
voltage and frequency.
cc: Chris Ball c...@laptop.org
Signed-off-by: Girish K S girish.shivananja...@linaro.org
---
Changes in v2:
deleted a unnecessary if else condition identified by subhash J
Changes in v1:
reduced the number of comparisons as per Hein's suggestion
drivers/mmc/core/mmc.c | 19 +++
include/linux/mmc/card.h | 4
2 files changed, 23 insertions(+), 0 deletions(-)
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 006e932..b9ef777 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -688,6 +688,25 @@ static int mmc_select_powerclass(struct mmc_card *card,
pwrclass_val = (pwrclass_val EXT_CSD_PWR_CL_4BIT_MASK)
EXT_CSD_PWR_CL_4BIT_SHIFT;
+ if (pwrclass_val = MMC_MAX_CURRENT_800)
Hi girish,
These checks can be made like ,
if (pwrclass_val MMC_MAX_CURRENT_800)
pwrclass_val = MMC_MAX_CURRENT_800;
Applicable in all below conditional checks.
I feel that should be OK. Since there will be no significant
improvement or side effects with the current implementation.
Thanks,
Amit D
+ pwrclass_val = MMC_MAX_CURRENT_800;
+ else if (pwrclass_val = MMC_MAX_CURRENT_600)
+ pwrclass_val = MMC_MAX_CURRENT_600;
+ else if (pwrclass_val = MMC_MAX_CURRENT_400)
+ pwrclass_val = MMC_MAX_CURRENT_400;
+ else
+ pwrclass_val = MMC_MAX_CURRENT_200;
+
+ if ((pwrclass_val == MMC_MAX_CURRENT_800)
+ !(card-host-caps MMC_CAP_MAX_CURRENT_800))
+ pwrclass_val = MMC_MAX_CURRENT_600;
+ if ((pwrclass_val == MMC_MAX_CURRENT_600)
+ !(card-host-caps MMC_CAP_MAX_CURRENT_600))
+ pwrclass_val = MMC_MAX_CURRENT_400;
+ if ((pwrclass_val == MMC_MAX_CURRENT_400)
+ !(card-host-caps MMC_CAP_MAX_CURRENT_400))
+ pwrclass_val = MMC_MAX_CURRENT_200;
+
/* If the power class is different from the default value */
if (pwrclass_val 0) {
err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index 9478a6b..c5e031a 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -195,6 +195,10 @@ struct mmc_part {
#define MMC_BLK_DATA_AREA_GP (12)
};
+#define MMC_MAX_CURRENT_200 (0)
+#define MMC_MAX_CURRENT_400 (7)
+#define MMC_MAX_CURRENT_600 (11)
+#define MMC_MAX_CURRENT_800 (13)
/*
* MMC device
*/
--
1.7.1
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