Re: [PATCH v4 drm-dp 3/8] drm/hisilicon/hibmc: Add dp serdes cfg in dp process

[Dmitry Baryshkov]

On Wed, Mar 05, 2025 at 07:26:42PM +0800, Yongbang Shi wrote:
> From: Baihan Li <libaihan@xxxxxxxxxx>
> 
> Add dp serdes cfg in link training process, and related adapting
> and modificating. Change some init values about training,
> because we want completely to negotiation process, so we start with
> the maximum rate and the electrical characteristic level is 0.

In the commit message there should be a mention, why are you also
changing hibmc_kms_init().

> 
> Signed-off-by: Baihan Li <libaihan@xxxxxxxxxx>
> Signed-off-by: Yongbang Shi <shiyongbang@xxxxxxxxxx>
> ---
> ChangeLog:
> v3 -> v4:
>   - add comments for if-statement of dp_init(), suggested by Dmitry Baryshkov.
> v2 -> v3:
>   - change commit to an imperative sentence, suggested by Dmitry Baryshkov.
>   - put HIBMC_DP_HOST_SERDES_CTRL in dp_serdes.h, suggested by Dmitry Baryshkov.
> v1 -> v2:
>   - splittting the patch and add more detailed the changes in the commit message, suggested by Dmitry Baryshkov.
> ---
>  1                                             |  0
>  .../gpu/drm/hisilicon/hibmc/dp/dp_config.h    |  1 +
>  drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c    |  5 ++-
>  drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.c  | 32 ++++++++++++++++---
>  drivers/gpu/drm/hisilicon/hibmc/dp/dp_reg.h   |  5 +++
>  .../gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c   | 12 +++----
>  6 files changed, 43 insertions(+), 12 deletions(-)
>  create mode 100644 1
> 

[...]

> @@ -121,9 +119,11 @@ static int hibmc_kms_init(struct hibmc_drm_private *priv)
>  		return ret;
>  	}
>  
> -	/* if DP existed, init DP */
> -	if ((readl(priv->mmio + HIBMC_DP_HOST_SERDES_CTRL) &
> -	     HIBMC_DP_HOST_SERDES_CTRL_MASK) == HIBMC_DP_HOST_SERDES_CTRL_VAL) {
> +	/* if the serdes reg is readable and is not equal to 0,
> +	 * DP existed, and init DP.
> +	 */

Nit: A typical format for block comments is:

  /*
   * Something Something Something
   */

Please follow it.

> +	ret = readl(priv->mmio + HIBMC_DP_HOST_SERDES_CTRL);
> +	if (ret) {
>  		ret = hibmc_dp_init(priv);
>  		if (ret)
>  			drm_err(dev, "failed to init dp: %d\n", ret);
> -- 
> 2.33.0
> 

-- 
With best wishes
Dmitry