linux-kernel - Re: [PATCH v3 05/43] drm/bridge: analogix_dp: Don't power bridge in analogix_dp

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Date:   Thu, 01 Mar 2018 09:19:54 +0100
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     Heiko Stübner <heiko@...ech.de>,
        linux-rockchip@...ts.infradead.org
Cc:     Thierry Escande <thierry.escande@...labora.com>,
        Archit Taneja <architt@...eaurora.org>,
        Inki Dae <inki.dae@...sung.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Sandy Huang <hjc@...k-chips.com>,
        Sean Paul <seanpaul@...omium.org>,
        David Airlie <airlied@...ux.ie>,
        Tomasz Figa <tfiga@...omium.org>,
        Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        Zain Wang <wzz@...k-chips.com>, Lin Huang <hl@...k-chips.com>,
        Douglas Anderson <dianders@...omium.org>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Yakir Yang <ykk@...k-chips.com>,
        Ørjan Eide <orjan.eide@....com>,
        Mark Yao <mark.yao@...k-chips.com>,
        Haixia Shi <hshi@...omium.org>
Subject: Re: [PATCH v3 05/43] drm/bridge: analogix_dp: Don't power bridge in
 analogix_dp_bind

Hi Heiko,

Thanks for adding me to this thread.

On 2018-02-28 16:20, Heiko Stübner wrote:
> Am Dienstag, 30. Januar 2018, 21:28:35 CET schrieb Thierry Escande:
>> From: zain wang <wzz@...k-chips.com>
>>
>> The bridge does not need to be powered in analogix_dp_bind(), so
>> remove the calls to pm_runtime_get()/phy_power_on()/analogix_dp_init_dp()
>> as well as their power-off counterparts.
>>
>> Cc: Stéphane Marchesin <marcheu@...omium.org>
>> Signed-off-by: zain wang <wzz@...k-chips.com>
>> Signed-off-by: Caesar Wang <wxt@...k-chips.com>
>> [the patch originally just removed the power_on portion, seanpaul removed
>> the power off code as well as improved the commit message]
>> Signed-off-by: Sean Paul <seanpaul@...omium.org>
>> Signed-off-by: Thierry Escande <thierry.escande@...labora.com>
>> ---
>>   drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 10 ----------
>>   1 file changed, 10 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c index
>> cb5e18d6ba04..1477ea9ba85d 100644
>> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> @@ -1382,11 +1382,6 @@ analogix_dp_bind(struct device *dev, struct
>> drm_device *drm_dev,
>>
>>   	pm_runtime_enable(dev);
>>
>> -	pm_runtime_get_sync(dev);
>> -	phy_power_on(dp->phy);
>> -
>> -	analogix_dp_init_dp(dp);
>> -
>>   	ret = devm_request_threaded_irq(&pdev->dev, dp->irq,
>>   					analogix_dp_hardirq,
>>   					analogix_dp_irq_thread,
>> @@ -1414,15 +1409,10 @@ analogix_dp_bind(struct device *dev, struct
>> drm_device *drm_dev, goto err_disable_pm_runtime;
>>   	}
>>
>> -	phy_power_off(dp->phy);
>> -	pm_runtime_put(dev);
>> -
>>   	return dp;
>>
>>   err_disable_pm_runtime:
>>
>> -	phy_power_off(dp->phy);
>> -	pm_runtime_put(dev);
>>   	pm_runtime_disable(dev);
>>
>>   	return ERR_PTR(ret);
> In general, this patch seems to also create the opposite than
> "drm/bridge: analogix_dp: Keep PHY powered between driver bind/unbind" [0]
>
> posted on monday?
>
> [0] https://patchwork.kernel.org/patch/10242493/

Well, my patch was a quick workaround to avoid board freeze.

This patch looks like a proper fix. Besides removing runtime pm and phy
power calls from dp_bind, it also removes dp register access done in
analogix_dp_init_dp, as there is really no need to touch registers in bind
operation.

The patchset however suffers from other issues on Exynos hardware. I 
will post
them in that thread.

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland