linux-kernel - Re: [PATCH v5 19/24] drm/msm/dsi: Add support for SM8750

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Message-ID: <c557a0a9-4505-4abf-87e2-448a1598c0c9@linaro.org>
Date: Mon, 19 May 2025 17:11:35 +0200
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: Abhinav Kumar <quic_abhinavk@...cinc.com>,
 Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Cc: Sean Paul <sean@...rly.run>,
 Marijn Suijten <marijn.suijten@...ainline.org>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>,
 Krishna Manikandan <quic_mkrishn@...cinc.com>,
 Jonathan Marek <jonathan@...ek.ca>, Kuogee Hsieh <quic_khsieh@...cinc.com>,
 Neil Armstrong <neil.armstrong@...aro.org>, Rob Clark <robdclark@...il.com>,
 Bjorn Andersson <andersson@...nel.org>,
 Michael Turquette <mturquette@...libre.com>, Stephen Boyd
 <sboyd@...nel.org>, linux-arm-msm@...r.kernel.org,
 dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 Rob Clark <robdclark@...omium.org>, linux-clk@...r.kernel.org,
 Srinivas Kandagatla <srini@...nel.org>
Subject: Re: [PATCH v5 19/24] drm/msm/dsi: Add support for SM8750

On 05/05/2025 23:28, Abhinav Kumar wrote:
>>>   static int dsi_clk_init(struct msm_dsi_host *msm_host)
>>>   {

Dmitry,

Please kindly trim the replies from unnecessary context. It makes it
much easier to find new content.

>>>   	struct platform_device *pdev = msm_host->pdev;
>>> @@ -370,6 +411,46 @@ int dsi_link_clk_set_rate_6g(struct msm_dsi_host *msm_host)
>>>   	return 0;
>>>   }
>>>   
>>> +int dsi_link_clk_set_rate_6g_v2_9(struct msm_dsi_host *msm_host)
>>> +{
>>> +	struct device *dev = &msm_host->pdev->dev;
>>> +	int ret;
>>> +
>>> +	/*
>>> +	 * DSI PHY PLLs have to be enabled to allow reparenting to them and
>>> +	 * setting the rates of pixel/byte clocks.
>>> +	 */
>>
>> According to the docs this should be handled by the
>> CLK_OPS_PARENT_ENABLE flag. Please correct me if I'm wrong.
>>
> 
> I am also interested to know that if we are indeed setting 
> CLK_OPS_PARENT_ENABLE flag, do we need this logic in the dsi driver.
> 
> If CLK_OPS_PARENT_ENABLE flag is not working as expected, shouldnt this 
> be something fixed on the clk fwk side?
> 

You are both right - CLK_OPS_PARENT_ENABLE handles this and I just did
not test that exact case (fixed dispcc driver, here dropping
clk_prepare_enable).

Best regards,
Krzysztof