Re: [Intel-gfx] [PATCH RESEND v4 2/6] drm/i915: Correctly enable blacklight adjustment via DPCD

[Jani Nikula]

On Tue, 18 Apr 2017, Puthikorn Voravootivat  wrote:
> intel_dp_aux_enable_backlight() assumed that the register
> BACKLIGHT_BRIGHTNESS_CONTROL_MODE can only has value 01
> (DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET) when initialize.
>
> This patch fixed that by handling all cases of that register.

Fixes like this should precede the functional changes, i.e. this should
be earlier in the series.

>
> Signed-off-by: Puthikorn Voravootivat 
> ---
>  drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 29 
> +--
>  1 file changed, 23 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c 
> b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> index 42f73d9a3ccf..f06c8381c74e 100644
> --- a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> +++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> @@ -101,15 +101,32 @@ static void intel_dp_aux_enable_backlight(struct 
> intel_connector *connector)
>  {
>   struct intel_dp *intel_dp = enc_to_intel_dp(>encoder->base);
>   uint8_t dpcd_buf = 0;
> + uint8_t edp_backlight_mode = 0;
>  
>   set_aux_backlight_enable(intel_dp, true);
>  
> - if ((drm_dp_dpcd_readb(_dp->aux,
> -DP_EDP_BACKLIGHT_MODE_SET_REGISTER, _buf) 
> == 1) &&
> - ((dpcd_buf & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK) ==
> -  DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET))
> - drm_dp_dpcd_writeb(_dp->aux, 
> DP_EDP_BACKLIGHT_MODE_SET_REGISTER,
> -(dpcd_buf | 
> DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD));

Ugh, that's really totally busted, since this actually enables the
product mode because it doesn't mask out the preset first. Thanks for
fixing this.

> + if (!drm_dp_dpcd_readb(_dp->aux,
> +DP_EDP_BACKLIGHT_MODE_SET_REGISTER, _buf)) {

I don't think there are any valid scenarious where this call would
return 0. if (... != 1) is the right check.

> + return;
> + }
> +
> + edp_backlight_mode = dpcd_buf & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
> +
> + switch (edp_backlight_mode) {
> + case DP_EDP_BACKLIGHT_CONTROL_MODE_PWM:
> + case DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET:
> + case DP_EDP_BACKLIGHT_CONTROL_MODE_PRODUCT:
> + dpcd_buf &= ~DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
> + dpcd_buf |= DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD;
> + drm_dp_dpcd_writeb(_dp->aux,
> + DP_EDP_BACKLIGHT_MODE_SET_REGISTER, dpcd_buf);

I wonder if the right order would be to set the mode first, and call
set_aux_backlight_enable() after that. I couldn't find anything about
that in the spec, but gut feeling says that would be better. Needs to be
a separate change though.

BR,
Jani.

> + break;
> +
> + /* Do nothing when it is already DPCD mode */
> + case DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD:
> + default:
> + break;
> + }
>  }
>  
>  static void intel_dp_aux_disable_backlight(struct intel_connector *connector)

-- 
Jani Nikula, Intel Open Source Technology Center
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Re: [Intel-gfx] [PATCH RESEND v4 2/6] drm/i915: Correctly enable blacklight adjustment via DPCD

[Manasi Navare]

On Tue, Apr 18, 2017 at 04:48:20PM -0700, Puthikorn Voravootivat wrote:
> intel_dp_aux_enable_backlight() assumed that the register
> BACKLIGHT_BRIGHTNESS_CONTROL_MODE can only has value 01
> (DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET) when initialize.
> 
> This patch fixed that by handling all cases of that register.
> 
> Signed-off-by: Puthikorn Voravootivat 
> ---
>  drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 29 
> +--
>  1 file changed, 23 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c 
> b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> index 42f73d9a3ccf..f06c8381c74e 100644
> --- a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> +++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> @@ -101,15 +101,32 @@ static void intel_dp_aux_enable_backlight(struct 
> intel_connector *connector)
>  {
>   struct intel_dp *intel_dp = enc_to_intel_dp(>encoder->base);
>   uint8_t dpcd_buf = 0;
> + uint8_t edp_backlight_mode = 0;
>  
>   set_aux_backlight_enable(intel_dp, true);
>  
> - if ((drm_dp_dpcd_readb(_dp->aux,
> -DP_EDP_BACKLIGHT_MODE_SET_REGISTER, _buf) 
> == 1) &&
> - ((dpcd_buf & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK) ==
> -  DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET))
> - drm_dp_dpcd_writeb(_dp->aux, 
> DP_EDP_BACKLIGHT_MODE_SET_REGISTER,
> -(dpcd_buf | 
> DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD));
> + if (!drm_dp_dpcd_readb(_dp->aux,
> +DP_EDP_BACKLIGHT_MODE_SET_REGISTER, _buf)) {
> + return;
> + }
> +
> + edp_backlight_mode = dpcd_buf & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
> +
> + switch (edp_backlight_mode) {
> + case DP_EDP_BACKLIGHT_CONTROL_MODE_PWM:
> + case DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET:
> + case DP_EDP_BACKLIGHT_CONTROL_MODE_PRODUCT:
> + dpcd_buf &= ~DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
> + dpcd_buf |= DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD;
> + drm_dp_dpcd_writeb(_dp->aux,
> + DP_EDP_BACKLIGHT_MODE_SET_REGISTER, dpcd_buf);
> + break;
> +
> + /* Do nothing when it is already DPCD mode */
> + case DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD:
> + default:
> + break;

Do you really need a break; here?

Manasi
> + }
>  }
>  
>  static void intel_dp_aux_disable_backlight(struct intel_connector *connector)
> -- 
> 2.12.2.816.g281164-goog
> 
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Re: [Intel-gfx] [PATCH RESEND v4 2/6] drm/i915: Correctly enable blacklight adjustment via DPCD

[Pandiyan, Dhinakaran]

Adjusting "blacklight" probably won't make a lot of difference even if
done correctly:) Typo in the patch subject.

-DK


On Tue, 2017-04-18 at 16:48 -0700, Puthikorn Voravootivat wrote:
> intel_dp_aux_enable_backlight() assumed that the register
> BACKLIGHT_BRIGHTNESS_CONTROL_MODE can only has value 01
> (DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET) when initialize.
> 
> This patch fixed that by handling all cases of that register.
> 
> Signed-off-by: Puthikorn Voravootivat 
> ---
>  drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 29 
> +--
>  1 file changed, 23 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c 
> b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> index 42f73d9a3ccf..f06c8381c74e 100644
> --- a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> +++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> @@ -101,15 +101,32 @@ static void intel_dp_aux_enable_backlight(struct 
> intel_connector *connector)
>  {
>   struct intel_dp *intel_dp = enc_to_intel_dp(>encoder->base);
>   uint8_t dpcd_buf = 0;
> + uint8_t edp_backlight_mode = 0;
>  
>   set_aux_backlight_enable(intel_dp, true);
>  
> - if ((drm_dp_dpcd_readb(_dp->aux,
> -DP_EDP_BACKLIGHT_MODE_SET_REGISTER, _buf) 
> == 1) &&
> - ((dpcd_buf & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK) ==
> -  DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET))
> - drm_dp_dpcd_writeb(_dp->aux, 
> DP_EDP_BACKLIGHT_MODE_SET_REGISTER,
> -(dpcd_buf | 
> DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD));
> + if (!drm_dp_dpcd_readb(_dp->aux,
> +DP_EDP_BACKLIGHT_MODE_SET_REGISTER, _buf)) {
> + return;
> + }
> +
> + edp_backlight_mode = dpcd_buf & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
> +
> + switch (edp_backlight_mode) {
> + case DP_EDP_BACKLIGHT_CONTROL_MODE_PWM:
> + case DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET:
> + case DP_EDP_BACKLIGHT_CONTROL_MODE_PRODUCT:
> + dpcd_buf &= ~DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
> + dpcd_buf |= DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD;
> + drm_dp_dpcd_writeb(_dp->aux,
> + DP_EDP_BACKLIGHT_MODE_SET_REGISTER, dpcd_buf);
> + break;
> +
> + /* Do nothing when it is already DPCD mode */
> + case DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD:
> + default:
> + break;
> + }
>  }
>  
>  static void intel_dp_aux_disable_backlight(struct intel_connector *connector)

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Re: [Intel-gfx] [PATCH RESEND v4 2/6] drm/i915: Correctly enable blacklight adjustment via DPCD

[Pandiyan, Dhinakaran]

On Tue, 2017-04-18 at 16:48 -0700, Puthikorn Voravootivat wrote:
> intel_dp_aux_enable_backlight() assumed that the register
> BACKLIGHT_BRIGHTNESS_CONTROL_MODE can only has value 01
> (DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET) when initialize.
> 
> This patch fixed that by handling all cases of that register.
> 
> Signed-off-by: Puthikorn Voravootivat 
> ---
>  drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 29 
> +--
>  1 file changed, 23 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c 
> b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> index 42f73d9a3ccf..f06c8381c74e 100644
> --- a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> +++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> @@ -101,15 +101,32 @@ static void intel_dp_aux_enable_backlight(struct 
> intel_connector *connector)
>  {
>   struct intel_dp *intel_dp = enc_to_intel_dp(>encoder->base);
>   uint8_t dpcd_buf = 0;
> + uint8_t edp_backlight_mode = 0;
>  
>   set_aux_backlight_enable(intel_dp, true);
>  
> - if ((drm_dp_dpcd_readb(_dp->aux,
> -DP_EDP_BACKLIGHT_MODE_SET_REGISTER, _buf) 
> == 1) &&
> - ((dpcd_buf & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK) ==
> -  DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET))
> - drm_dp_dpcd_writeb(_dp->aux, 
> DP_EDP_BACKLIGHT_MODE_SET_REGISTER,
> -(dpcd_buf | 
> DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD));
> + if (!drm_dp_dpcd_readb(_dp->aux,
> +DP_EDP_BACKLIGHT_MODE_SET_REGISTER, _buf)) {
> + return;
> + }
> +
> + edp_backlight_mode = dpcd_buf & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
> +
> + switch (edp_backlight_mode) {
> + case DP_EDP_BACKLIGHT_CONTROL_MODE_PWM:
> + case DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET:
> + case DP_EDP_BACKLIGHT_CONTROL_MODE_PRODUCT:
> + dpcd_buf &= ~DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
> + dpcd_buf |= DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD;
> + drm_dp_dpcd_writeb(_dp->aux,
> + DP_EDP_BACKLIGHT_MODE_SET_REGISTER, dpcd_buf);


You check the return value for _readb() above, but don't check for the
_writeb() here.



> + break;
> +
> + /* Do nothing when it is already DPCD mode */
> + case DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD:
> + default:
> + break;
> + }
>  }
>  
>  static void intel_dp_aux_disable_backlight(struct intel_connector *connector)

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[Intel-gfx] [PATCH RESEND v4 2/6] drm/i915: Correctly enable blacklight adjustment via DPCD

[Puthikorn Voravootivat]

intel_dp_aux_enable_backlight() assumed that the register
BACKLIGHT_BRIGHTNESS_CONTROL_MODE can only has value 01
(DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET) when initialize.

This patch fixed that by handling all cases of that register.

Signed-off-by: Puthikorn Voravootivat 
---
 drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 29 +--
 1 file changed, 23 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c 
b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
index 42f73d9a3ccf..f06c8381c74e 100644
--- a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
+++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
@@ -101,15 +101,32 @@ static void intel_dp_aux_enable_backlight(struct 
intel_connector *connector)
 {
struct intel_dp *intel_dp = enc_to_intel_dp(>encoder->base);
uint8_t dpcd_buf = 0;
+   uint8_t edp_backlight_mode = 0;
 
set_aux_backlight_enable(intel_dp, true);
 
-   if ((drm_dp_dpcd_readb(_dp->aux,
-  DP_EDP_BACKLIGHT_MODE_SET_REGISTER, _buf) 
== 1) &&
-   ((dpcd_buf & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK) ==
-DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET))
-   drm_dp_dpcd_writeb(_dp->aux, 
DP_EDP_BACKLIGHT_MODE_SET_REGISTER,
-  (dpcd_buf | 
DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD));
+   if (!drm_dp_dpcd_readb(_dp->aux,
+  DP_EDP_BACKLIGHT_MODE_SET_REGISTER, _buf)) {
+   return;
+   }
+
+   edp_backlight_mode = dpcd_buf & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
+
+   switch (edp_backlight_mode) {
+   case DP_EDP_BACKLIGHT_CONTROL_MODE_PWM:
+   case DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET:
+   case DP_EDP_BACKLIGHT_CONTROL_MODE_PRODUCT:
+   dpcd_buf &= ~DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
+   dpcd_buf |= DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD;
+   drm_dp_dpcd_writeb(_dp->aux,
+   DP_EDP_BACKLIGHT_MODE_SET_REGISTER, dpcd_buf);
+   break;
+
+   /* Do nothing when it is already DPCD mode */
+   case DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD:
+   default:
+   break;
+   }
 }
 
 static void intel_dp_aux_disable_backlight(struct intel_connector *connector)
-- 
2.12.2.816.g281164-goog

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