linux-kernel - Re: [RFC][PATCH 1/3] drm/bridge: adv7511: Rework adv7511_power_on/off() so they can be reused internally

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Message-ID: <CALAqxLVNUhrRy6xtaOHCZLyPEWGxuAi4Pduu1aBoktn1DWFwyg@mail.gmail.com>
Date:   Tue, 22 Nov 2016 00:16:55 -0800
From:   John Stultz <john.stultz@...aro.org>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     lkml <linux-kernel@...r.kernel.org>,
        David Airlie <airlied@...ux.ie>,
        Archit Taneja <architt@...eaurora.org>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Lars-Peter Clausen <lars@...afoo.de>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>
Subject: Re: [RFC][PATCH 1/3] drm/bridge: adv7511: Rework adv7511_power_on/off()
 so they can be reused internally

On Tue, Nov 22, 2016 at 12:14 AM, Laurent Pinchart
<laurent.pinchart@...asonboard.com> wrote:
> Hi John,
>
> Thank you for the patch.
>
> On Monday 21 Nov 2016 16:37:30 John Stultz wrote:
>> In chasing down issues with EDID probing, I found some
>> duplicated but incomplete logic used to power the chip on and
>> off.
>>
>> This patch refactors the adv7511_power_on/off functions, so
>> they can be used for internal needs, and replaces duplicative
>> logic that powers the chip on and off around the EDID probing
>> with the common logic.
>>
>> Cc: David Airlie <airlied@...ux.ie>
>> Cc: Archit Taneja <architt@...eaurora.org>
>> Cc: Wolfram Sang <wsa+renesas@...g-engineering.com>
>> Cc: Lars-Peter Clausen <lars@...afoo.de>
>> Cc: Laurent Pinchart <laurent.pinchart@...asonboard.com>
>> Cc: dri-devel@...ts.freedesktop.org
>> Signed-off-by: John Stultz <john.stultz@...aro.org>
>> ---
>>  drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 30 +++++++++++--------------
>>  1 file changed, 14 insertions(+), 16 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
>> b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c index 8dba729..b240e05
>> 100644
>> --- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
>> +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
>> @@ -325,7 +325,7 @@ static void adv7511_set_link_config(struct adv7511
>> *adv7511, adv7511->rgb = config->input_colorspace == HDMI_COLORSPACE_RGB;
>>  }
>>
>> -static void adv7511_power_on(struct adv7511 *adv7511)
>> +static void __adv7511_power_on(struct adv7511 *adv7511)
>>  {
>>       adv7511->current_edid_segment = -1;
>>
>> @@ -343,6 +343,7 @@ static void adv7511_power_on(struct adv7511 *adv7511)
>>                            ADV7511_INT1_DDC_ERROR);
>>       }
>>
>> +
>
> This isn't needed.

Apologies. I saw this right after I sent it!

>>       /*
>>        * Per spec it is allowed to pulse the HPD signal to indicate that the
>>        * EDID information has changed. Some monitors do this when they
> wakeup
>> @@ -362,11 +363,15 @@ static void adv7511_power_on(struct adv7511 *adv7511)
>>
>>       if (adv7511->type == ADV7533)
>>               adv7533_dsi_power_on(adv7511);
>> +}
>>
>> +static void adv7511_power_on(struct adv7511 *adv7511)
>> +{
>> +     __adv7511_power_on(adv7511);
>>       adv7511->powered = true;
>>  }
>>
>> -static void adv7511_power_off(struct adv7511 *adv7511)
>> +static void __adv7511_power_off(struct adv7511 *adv7511)
>>  {
>>       /* TODO: setup additional power down modes */
>>       regmap_update_bits(adv7511->regmap, ADV7511_REG_POWER,
>> @@ -376,7 +381,11 @@ static void adv7511_power_off(struct adv7511 *adv7511)
>>
>>       if (adv7511->type == ADV7533)
>>               adv7533_dsi_power_off(adv7511);
>> +}
>>
>> +static void adv7511_power_off(struct adv7511 *adv7511)
>> +{
>> +     __adv7511_power_off(adv7511);
>>       adv7511->powered = false;
>>  }
>>
>> @@ -545,24 +554,13 @@ static int adv7511_get_modes(struct adv7511 *adv7511,
>>       unsigned int count;
>>
>>       /* Reading the EDID only works if the device is powered */
>> -     if (!adv7511->powered) {
>> -             regmap_update_bits(adv7511->regmap, ADV7511_REG_POWER,
>> -                                ADV7511_POWER_POWER_DOWN, 0);
>> -             if (adv7511->i2c_main->irq) {
>> -                     regmap_write(adv7511->regmap,
> ADV7511_REG_INT_ENABLE(0),
>> -                                  ADV7511_INT0_EDID_READY);
>> -                     regmap_write(adv7511->regmap,
> ADV7511_REG_INT_ENABLE(1),
>> -                                  ADV7511_INT1_DDC_ERROR);
>> -             }
>> -             adv7511->current_edid_segment = -1;
>> -     }
>> +     if (!adv7511->powered)
>> +             __adv7511_power_on(adv7511);
>
> The __adv7511_power_on() function does more than the above, in particular it
> performs an expensive regcache_sync() and calls adv7533_dsi_power_on() for the
> ADV7533. Don't those operations have side effects that are either not wanted
> or not needed here ? In any case this patch modifies the behaviour of the
> driver, which needs to be documented in the kernel message.

Sorry, what do you mean by kernel message? Commit message, maybe?

Fair point, I'll review the adv7533_dsi_power_on bits and see if they
should move out to the external function rather then the internal one.
Similarly for the regcache_sync.

Thanks so much for the review!

thanks
-john