[PATCH] drm/msm/mdp5: fix reading hw revision on db410c platform

[Abhinav Kumar]

On 11/24/2022 4:02 PM, Dmitry Baryshkov wrote:
> Since the commit commit c6122688f265 ("drm/msm/mdp5: stop overriding
> drvdata") reading the MDP5 hw revision on db410c will crash the board
> as the MDSS_GDSC is not enabled. Revert a part of the offending commit
> (moving rpm enablement) and set priv->kms earlier. This make it possible
> to use pm_runtime_get_sync() during read_mdp_hw_revision(), which will
> power up both the MDP5 and MDSS devices.
> 

This is the exact concern I had even when c6122688f265 was pushed.

https://patchwork.freedesktop.org/patch/508334/#comment_917689

Was the response given that time not correct then?

https://patchwork.freedesktop.org/patch/508334/#comment_917713
> Fixes: c6122688f265 ("drm/msm/mdp5: stop overriding drvdata")
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
> ---
>   drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c | 17 ++++++++---------
>   1 file changed, 8 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c b/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c
> index b46f983f2b46..29ae5c9613f3 100644
> --- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c
> +++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c
> @@ -519,10 +519,9 @@ static void read_mdp_hw_revision(struct mdp5_kms *mdp5_kms,
>   	struct device *dev = &mdp5_kms->pdev->dev;
>   	u32 version;
>   
> -	/* Manually enable the MDP5, as pm runtime isn't usable yet. */
> -	mdp5_enable(mdp5_kms);
> +	pm_runtime_get_sync(dev);
>   	version = mdp5_read(mdp5_kms, REG_MDP5_HW_VERSION);
> -	mdp5_disable(mdp5_kms);
> +	pm_runtime_put_sync(dev);
>   
>   	*major = FIELD(version, MDP5_HW_VERSION_MAJOR);
>   	*minor = FIELD(version, MDP5_HW_VERSION_MINOR);
> @@ -839,6 +838,12 @@ static int mdp5_init(struct platform_device *pdev, struct drm_device *dev)
>   	 */
>   	clk_set_rate(mdp5_kms->core_clk, 200000000);
>   
> +	/* set uninit-ed kms */
> +	priv->kms = &mdp5_kms->base.base;
> +
> +	pm_runtime_enable(&pdev->dev);
> +	mdp5_kms->rpm_enabled = true;
> +
>   	read_mdp_hw_revision(mdp5_kms, &major, &minor);
>   
>   	mdp5_kms->cfg = mdp5_cfg_init(mdp5_kms, major, minor);
> @@ -887,12 +892,6 @@ static int mdp5_init(struct platform_device *pdev, struct drm_device *dev)
>   	if (ret)
>   		goto fail;
>   
> -	/* set uninit-ed kms */
> -	priv->kms = &mdp5_kms->base.base;
> -
> -	pm_runtime_enable(&pdev->dev);
> -	mdp5_kms->rpm_enabled = true;
> -
>   	return 0;
>   fail:
>   	if (mdp5_kms)