[PATCH drm-dp 10/10] drm/hisilicon/hibmc: fix no showing problem with loading hibmc manually

[Dmitry Baryshkov]

On Fri, May 30, 2025 at 05:54:32PM +0800, Yongbang Shi wrote:
> From: Baihan Li <libaihan at huawei.com>
> 
> When using command rmmod and insmod, there is no showing in second time
> insmoding. Because DP controller won't send HPD signals, if connection
> doesn't change or controller isn't reset. So add reset before unreset
> in hibmc_dp_hw_init().
> 
> Fixes: 94ee73ee3020 ("drm/hisilicon/hibmc: add dp hw moduel in hibmc driver")

Technically... yes and no. The function was written this way in that
commit, however HPD signals were not handled until the latter commit.

> Signed-off-by: Baihan Li <libaihan at huawei.com>
> ---
>  drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
> index 4f93d60b932b..e1b9589ce639 100644
> --- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
> +++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
> @@ -172,13 +172,15 @@ int hibmc_dp_hw_init(struct hibmc_dp *dp)
>  	dp_dev->link.cap.lanes = 0x2;
>  	dp_dev->link.cap.link_rate = DP_LINK_BW_8_1;
>  
> -	/* hdcp data */
> -	writel(HIBMC_DP_HDCP, dp_dev->base + HIBMC_DP_HDCP_CFG);
>  	/* int init */
>  	writel(0, dp_dev->base + HIBMC_DP_INTR_ENABLE);
>  	writel(HIBMC_DP_INT_RST, dp_dev->base + HIBMC_DP_INTR_ORIGINAL_STATUS);
>  	/* rst */
> +	writel(0, dp_dev->base + HIBMC_DP_DPTX_RST_CTRL);
> +	usleep_range(30, 50);
>  	writel(HIBMC_DP_DPTX_RST, dp_dev->base + HIBMC_DP_DPTX_RST_CTRL);
> +	/* hdcp data */
> +	writel(HIBMC_DP_HDCP, dp_dev->base + HIBMC_DP_HDCP_CFG);

There are two independent changes here. Split them into two commits.

>  	/* clock enable */
>  	writel(HIBMC_DP_CLK_EN, dp_dev->base + HIBMC_DP_DPTX_CLK_CTRL);
>  
> -- 
> 2.33.0
> 

-- 
With best wishes
Dmitry