linux-kernel - Re: [PATCH v5 12/20] drm/rockchip: analogix_dp: Add support to get panel from the DP AUX bus

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Message-ID: <ba369b98-9a2a-421a-9251-4db3c1dcedd9@rock-chips.com>
Date: Wed, 22 Jan 2025 17:37:53 +0800
From: Damon Ding <damon.ding@...k-chips.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: heiko@...ech.de, robh@...nel.org, krzk+dt@...nel.org,
 conor+dt@...nel.org, rfoss@...nel.org, vkoul@...nel.org,
 sebastian.reichel@...labora.com, cristian.ciocaltea@...labora.com,
 l.stach@...gutronix.de, andy.yan@...k-chips.com, hjc@...k-chips.com,
 algea.cao@...k-chips.com, kever.yang@...k-chips.com,
 dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-rockchip@...ts.infradead.org,
 linux-kernel@...r.kernel.org, linux-phy@...ts.infradead.org
Subject: Re: [PATCH v5 12/20] drm/rockchip: analogix_dp: Add support to get
 panel from the DP AUX bus

Hi Dmitry,

On 2025/1/22 16:17, Damon Ding wrote:
> Hi Dmitry,
> 
> On 2025/1/9 20:48, Dmitry Baryshkov wrote:
>> On Thu, Jan 09, 2025 at 11:27:17AM +0800, Damon Ding wrote:
>>> Move drm_of_find_panel_or_bridge() a little later and combine it with
>>> component_add() into a new function rockchip_dp_link_panel(). The 
>>> function
>>> will serve as done_probing() callback of devm_of_dp_aux_populate_bus(),
>>> aiding to support for obtaining the eDP panel via the DP AUX bus.
>>>
>>> If failed to get the panel from the DP AUX bus, it will then try the 
>>> other
>>> way to get panel information through the platform bus.
>>>
>>> In addition, use dev_err() instead of drm_err() in rockchip_dp_poweron()
>>> , which will be called before rockchip_dp_bind().
>>>
>>> Signed-off-by: Damon Ding <damon.ding@...k-chips.com>
>>>
>>> ---
>>>
>>> Changes in v4:
>>> - Use done_probing() to call drm_of_find_panel_or_bridge() and
>>>    component_add() when getting panel from the DP AUX bus
>>>
>>> Changes in v5:
>>> - Use the functions exported by the Analogix side to get the pointers of
>>>    struct analogix_dp_plat_data and struct drm_dp_aux.
>>> - Use dev_err() instead of drm_err() in rockchip_dp_poweron().
>>>
>>> ---
>>>   .../gpu/drm/rockchip/analogix_dp-rockchip.c   | 41 ++++++++++++++-----
>>>   1 file changed, 30 insertions(+), 11 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c b/ 
>>> drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
>>> index 0957d3c5d31d..3ae01b870f49 100644
>>> --- a/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
>>> +++ b/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
>>> @@ -124,13 +124,13 @@ static int rockchip_dp_poweron(struct 
>>> analogix_dp_plat_data *plat_data)
>>>       ret = clk_prepare_enable(dp->pclk);
>>>       if (ret < 0) {
>>> -        drm_err(dp->drm_dev, "failed to enable pclk %d\n", ret);
>>> +        dev_err(dp->dev, "failed to enable pclk %d\n", ret);
>>
>>
>> why?
>>
> 
> The &rockchip_dp_device.drm_dev will be assigned in rockchip_dp_bind(), 
> which is called after probing process. The PM operations have been 
> advanced to the probing for the AUX transmission, so the dev_err() may 
> be better than drm_err().
> 

Using drm_...() uniformly may be better [0].

>>>           return ret;
>>>       }
>>>       ret = rockchip_dp_pre_init(dp);
>>>       if (ret < 0) {
>>> -        drm_err(dp->drm_dev, "failed to dp pre init %d\n", ret);
>>> +        dev_err(dp->dev, "failed to dp pre init %d\n", ret);
>>>           clk_disable_unprepare(dp->pclk);
>>>           return ret;
>>>       }
>>

Best regards,
Damon

[0]https://patchwork.kernel.org/project/linux-rockchip/patch/20250109032725.1102465-6-damon.ding@rock-chips.com/#26209891