Re: [PATCH 3/6] ARM: dts: am437x-gp-evm: Don't use read/write wait monitoring
On Thursday 04 September 2014 03:16 PM, Roger Quadros wrote: [...] This patch is for the 3.17 bug fix cycle. Implementing NAND device ready mechanism is a new feature (for DT case) and I will work on it for future versions. Also I'm not de-scoping wait-pin (or more correctly device ready) mechanism for NAND. The dts file still contains "wait-pin = <0>" property. This will be used to monitor the NAND device ready status via GPMC status or GPMC interrupt. But this is not for 3.17 bug fix cycle. Ok Thanks, that good to know. So for this whole series Reviewed-by: Pekon Gupta with regards, pekon Powered by BigRock.com -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 3/6] ARM: dts: am437x-gp-evm: Don't use read/write wait monitoring
+ Sekhar. Hi Pekon, On 09/03/2014 08:29 PM, pekon wrote: > Hi Roger, > > On Wednesday 03 September 2014 02:02 PM, Roger Quadros wrote: >> Hi Pekon, >> >> On 09/02/2014 10:02 PM, pekon wrote: >>> Hi Roger, >>> >>> >>> On Tuesday 02 September 2014 07:27 PM, Roger Quadros wrote: NAND uses wait pin only to indicate device readiness after a block/page operation. It is not use to extend individual read/write cycle and so read/write wait pin monitoring must be disabled for NAND. >>> I think this is incorrect assumption. NAND framework allows >>> wait-pin monitoring at end of each read/write cycle. Please >>> refer following code in drivers/mtd/nand/nand_base.c >>> @@ void nand_wait_ready(...) >>> >>> - nand_wait_ready() calls controller-driver specific call-back >>>for chip->dev_ready(). >> >> It is important to note that this NAND device ready mechanism is different >> from >> GPMC inter cycle wait state mechanism controlled by the read/write monitoring >> bits. The same WAIT pin is used in both the cases. >> >> For more details about NAND use case refer to >> >> AM437x TRM: >> Section: 9.1.3.3.12.2 NAND Device-Ready Pin >> >> below excerpt from there >> "To avoid a time-out caused by a block/page opening delay in NAND flash, >> disable the wait pin monitoring >> for read and write accesses (that is, set the GPMC_CONFIG1_i[[21] >> WAITWRITEMONITORING and >> GPMC_CONFIG1_i[[22] WAITREADMONITORING bits to 0): >> > > I re-read the AM437x TRM, and the section you mentioned above. > > - > *9.1.3.3.12.2 NAND Device-Ready Pin* > The NAND memory device provides a ready pin to indicate data availability > after a block/page opening and to indicate that data programming is complete. > The ready pin can be connected to one of the WAIT GPMC input pins; data read > accesses must not be tried when the ready pin is sampled inactive (device is > not ready) even if the associated chip-select WAITREADMONITORING bit field is > set. The duration of the NAND device busy state after the block/page opening > is so long (up to 50 μs) that accesses occurring when the ready pin is > sampled inactive can stall GPMC access and eventually cause a system time-out. > If a read access to a NAND flash is done using the wait monitoring mode, the > device is blocked during a page opening, and so is the GPMC. If the correct > settings are used, other chip-selects can be used while > the memory processes the page opening command. > ... > - > > It's clearly written that wait-pin monitoring is used for read/write > (programs) access, and GPMC is blocked till wait signal is asserted during > reads. And you cut out the most important part where it says keep read/write wait monitoring disabled for NAND. pasting again here. "To avoid a time-out caused by a block/page opening delay in NAND flash, disable the wait pin monitoring for read and write accesses (that is, set the GPMC_CONFIG1_i[[21] WAITWRITEMONITORING and GPMC_CONFIG1_i[[22] WAITREADMONITORING bits to 0 and use one of the following methods instead: •Use software to poll the WAITnSTS bit (n = 0 to 1) of the GPMC_STS register. •Configure an interrupt that is generated on the WAIT signal change (through the GPMC_IRQEN [11-8] bits). Even if the READWAITMONITORING bit is not set, the external memory nR/B pinstatus is captured in the programmed WAIT bit in the GPMC_STS register. The READWAITMONITORING bit method must be used for other memories than NAND flash, if they require the use of a WAIT signal." > Also, on NAND there can be no read/write access except at page-level And how are command/address inputs sent? ;) > so wait-pin monitoring is implicitly related to read/write accesses. > However, whether you use it or not is purely user's choice, but it > has performance impact. I don't know what you are talking about. I have tried to explain many times but you fail to understand. Nand device ready pin is not same as the wait pin used on other memories where it is used to extend each read/write cycle (by inserting wait state). It is only used to indicate that the NAND device is busy during a block/page operation, so that new commands won't be sent to it by the host processor. This is different from TI GPMC wait monitoring. You have to monitor this device ready pin out of band like polling the status bit or using GPMC interrupt on wait pin transition. Looks like you are getting confused because the same WAIT pin on the SoC is used to get this device ready pin status into the SoC. > > You are probably seeing timeout condition when enabling wait-pin > monitoring, and this can be due to multiple reasons like; > (1) incorrect pin-mux configuration (like directions, pull-up etc) > (2) incorrect board-level pull-up > (3) incorrect driver setting, like though wait-pin is enabled but > wrong wait-pin is being monitored. No for all the 3. > > I request you to fix this instead of disabling it com
Re: [PATCH 3/6] ARM: dts: am437x-gp-evm: Don't use read/write wait monitoring
Hi Roger,
On Wednesday 03 September 2014 02:02 PM, Roger Quadros wrote:
Hi Pekon,
On 09/02/2014 10:02 PM, pekon wrote:
Hi Roger,
On Tuesday 02 September 2014 07:27 PM, Roger Quadros wrote:
NAND uses wait pin only to indicate device readiness after
a block/page operation. It is not use to extend individual
read/write cycle and so read/write wait pin monitoring must
be disabled for NAND.
I think this is incorrect assumption. NAND framework allows
wait-pin monitoring at end of each read/write cycle. Please
refer following code in drivers/mtd/nand/nand_base.c
@@ void nand_wait_ready(...)
- nand_wait_ready() calls controller-driver specific call-back
for chip->dev_ready().
It is important to note that this NAND device ready mechanism is different from
GPMC inter cycle wait state mechanism controlled by the read/write monitoring
bits. The same WAIT pin is used in both the cases.
For more details about NAND use case refer to
AM437x TRM:
Section: 9.1.3.3.12.2 NAND Device-Ready Pin
below excerpt from there
"To avoid a time-out caused by a block/page opening delay in NAND flash,
disable the wait pin monitoring
for read and write accesses (that is, set the GPMC_CONFIG1_i[[21]
WAITWRITEMONITORING and
GPMC_CONFIG1_i[[22] WAITREADMONITORING bits to 0):
I re-read the AM437x TRM, and the section you mentioned above.
-
*9.1.3.3.12.2 NAND Device-Ready Pin*
The NAND memory device provides a ready pin to indicate data
availability after a block/page opening and to indicate that data
programming is complete. The ready pin can be connected to one of the
WAIT GPMC input pins; data read accesses must not be tried when the
ready pin is sampled inactive (device is not ready) even if the
associated chip-select WAITREADMONITORING bit field is set. The duration
of the NAND device busy state after the block/page opening is so long
(up to 50 μs) that accesses occurring when the ready pin is sampled
inactive can stall GPMC access and eventually cause a system time-out.
If a read access to a NAND flash is done using the wait monitoring mode,
the device is blocked during a page opening, and so is the GPMC. If the
correct settings are used, other chip-selects can be used while
the memory processes the page opening command.
...
-
It's clearly written that wait-pin monitoring is used for read/write
(programs) access, and GPMC is blocked till wait signal is asserted
during reads.
Also, on NAND there can be no read/write access except at page-level
so wait-pin monitoring is implicitly related to read/write accesses.
However, whether you use it or not is purely user's choice, but it
has performance impact.
You are probably seeing timeout condition when enabling wait-pin
monitoring, and this can be due to multiple reasons like;
(1) incorrect pin-mux configuration (like directions, pull-up etc)
(2) incorrect board-level pull-up
(3) incorrect driver setting, like though wait-pin is enabled but
wrong wait-pin is being monitored.
I request you to fix this instead of disabling it completely,
as you should see significant NAND throughput increase once this
feature works correctly.
- chip->dev_ready in-case of OMAP NAND drivers is set in
drivers/mtd/nand/omap2.c during probe.
if (pdata->dev_ready) {
nand_chip->dev_ready = omap_dev_ready;
nand_chip->chip_delay = 0;
}
Problem is we don't set pdata->dev_ready correctly as part
of platform-data dring GPMC initialization. This was what my
earlier patch for wait-pin monitoring about. But it was a
quick fix for NAND devices.
So, I suggest to fix wait-pin monitoring instead of de-scoping
it from DTS as wait-pin monitoring should boast the NAND
performance significantly.
(please see if you can find an old mail thread which had some
good feedbacks from Ezequiel and Javier about wait-pin monitoring).
This is to get the device ready mechanism work and has nothing to do with
GPMC wait monitoring. Instead the WAIT pin is used to generate the GPMC
interrupt based on the WAIT pin polarity.
To monitor NAND device ready status
from TRM
"-Use software to poll the WAITnSTS bit (n = 0 to 1) of the GPMC_STS register.
OR
-Configure an interrupt that is generated on the WAIT signal change (through the
GPMC_IRQEN [11-8] bits)"
[...]
This patch also gets rid of the below warning when NAND is
accessed for the first time.
omap_l3_noc 4400.ocp: L3 application error: target 13 mod:1 (unclearable)
Can you debug this further.
This warning probably comes when driver tries to access some
"reserved" addresses. Or violate read/write bits.
It is caused because of incorrectly enabled the GPMC wait monitoring. Disabling
the
wait monitoring gets rid of this error. I don't understand what else I should
debug
I'm not sure how a NAND or GPMC feature can cause omap_l3_noc: L3
application error ?
But now as I re-read the text, its probably the L3 interconnect timeout
error due to no response from GPMC. The
Re: [PATCH 3/6] ARM: dts: am437x-gp-evm: Don't use read/write wait monitoring
Hi Pekon,
On 09/02/2014 10:02 PM, pekon wrote:
> Hi Roger,
>
>
> On Tuesday 02 September 2014 07:27 PM, Roger Quadros wrote:
>> NAND uses wait pin only to indicate device readiness after
>> a block/page operation. It is not use to extend individual
>> read/write cycle and so read/write wait pin monitoring must
>> be disabled for NAND.
>>
> I think this is incorrect assumption. NAND framework allows
> wait-pin monitoring at end of each read/write cycle. Please
> refer following code in drivers/mtd/nand/nand_base.c
> @@ void nand_wait_ready(...)
>
> - nand_wait_ready() calls controller-driver specific call-back
> for chip->dev_ready().
It is important to note that this NAND device ready mechanism is different from
GPMC inter cycle wait state mechanism controlled by the read/write monitoring
bits. The same WAIT pin is used in both the cases.
For more details about NAND use case refer to
AM437x TRM:
Section: 9.1.3.3.12.2 NAND Device-Ready Pin
below excerpt from there
"To avoid a time-out caused by a block/page opening delay in NAND flash,
disable the wait pin monitoring
for read and write accesses (that is, set the GPMC_CONFIG1_i[[21]
WAITWRITEMONITORING and
GPMC_CONFIG1_i[[22] WAITREADMONITORING bits to 0):
>
> - chip->dev_ready in-case of OMAP NAND drivers is set in
> drivers/mtd/nand/omap2.c during probe.
> if (pdata->dev_ready) {
> nand_chip->dev_ready = omap_dev_ready;
> nand_chip->chip_delay = 0;
> }
>
> Problem is we don't set pdata->dev_ready correctly as part
> of platform-data dring GPMC initialization. This was what my
> earlier patch for wait-pin monitoring about. But it was a
> quick fix for NAND devices.
>
> So, I suggest to fix wait-pin monitoring instead of de-scoping
> it from DTS as wait-pin monitoring should boast the NAND
> performance significantly.
> (please see if you can find an old mail thread which had some
> good feedbacks from Ezequiel and Javier about wait-pin monitoring).
This is to get the device ready mechanism work and has nothing to do with
GPMC wait monitoring. Instead the WAIT pin is used to generate the GPMC
interrupt based on the WAIT pin polarity.
To monitor NAND device ready status
from TRM
"-Use software to poll the WAITnSTS bit (n = 0 to 1) of the GPMC_STS register.
OR
-Configure an interrupt that is generated on the WAIT signal change (through
the GPMC_IRQEN [11-8] bits)"
>
> [...]
>
>> This patch also gets rid of the below warning when NAND is
>> accessed for the first time.
>>
>> omap_l3_noc 4400.ocp: L3 application error: target 13 mod:1 (unclearable)
>>
> Can you debug this further.
> This warning probably comes when driver tries to access some
> "reserved" addresses. Or violate read/write bits.
It is caused because of incorrectly enabled the GPMC wait monitoring. Disabling
the
wait monitoring gets rid of this error. I don't understand what else I should
debug and why.
cheers,
-roger
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Re: [PATCH 3/6] ARM: dts: am437x-gp-evm: Don't use read/write wait monitoring
Hi Roger,
On Tuesday 02 September 2014 07:27 PM, Roger Quadros wrote:
NAND uses wait pin only to indicate device readiness after
a block/page operation. It is not use to extend individual
read/write cycle and so read/write wait pin monitoring must
be disabled for NAND.
I think this is incorrect assumption. NAND framework allows
wait-pin monitoring at end of each read/write cycle. Please
refer following code in drivers/mtd/nand/nand_base.c
@@ void nand_wait_ready(...)
- nand_wait_ready() calls controller-driver specific call-back
for chip->dev_ready().
- chip->dev_ready in-case of OMAP NAND drivers is set in
drivers/mtd/nand/omap2.c during probe.
if (pdata->dev_ready) {
nand_chip->dev_ready = omap_dev_ready;
nand_chip->chip_delay = 0;
}
Problem is we don't set pdata->dev_ready correctly as part
of platform-data dring GPMC initialization. This was what my
earlier patch for wait-pin monitoring about. But it was a
quick fix for NAND devices.
So, I suggest to fix wait-pin monitoring instead of de-scoping
it from DTS as wait-pin monitoring should boast the NAND
performance significantly.
(please see if you can find an old mail thread which had some
good feedbacks from Ezequiel and Javier about wait-pin monitoring).
[...]
This patch also gets rid of the below warning when NAND is
accessed for the first time.
omap_l3_noc 4400.ocp: L3 application error: target 13 mod:1 (unclearable)
Can you debug this further.
This warning probably comes when driver tries to access some
"reserved" addresses. Or violate read/write bits.
with regards, pekon
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[PATCH 3/6] ARM: dts: am437x-gp-evm: Don't use read/write wait monitoring
NAND uses wait pin only to indicate device readiness after a block/page operation. It is not use to extend individual read/write cycle and so read/write wait pin monitoring must be disabled for NAND. This patch also gets rid of the below warning when NAND is accessed for the first time. omap_l3_noc 4400.ocp: L3 application error: target 13 mod:1 (unclearable) Signed-off-by: Roger Quadros --- arch/arm/boot/dts/am437x-gp-evm.dts | 2 -- 1 file changed, 2 deletions(-) diff --git a/arch/arm/boot/dts/am437x-gp-evm.dts b/arch/arm/boot/dts/am437x-gp-evm.dts index 402249e..ff4af7b 100644 --- a/arch/arm/boot/dts/am437x-gp-evm.dts +++ b/arch/arm/boot/dts/am437x-gp-evm.dts @@ -443,8 +443,6 @@ gpmc,rd-cycle-ns = <40>; gpmc,wr-cycle-ns = <40>; gpmc,wait-pin = <0>; - gpmc,wait-on-read; - gpmc,wait-on-write; gpmc,bus-turnaround-ns = <0>; gpmc,cycle2cycle-delay-ns = <0>; gpmc,clk-activation-ns = <0>; -- 1.8.3.2 -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
