linux-kernel - Re: [PATCH v2 drm-dp 09/10] drm/hisilicon/hibmc: fix no showing problem with loading hibmc manually

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Message-ID: <xulg22zaxstsp6jyalonxapqpj3wj4raacnvsv5jpuaebxn4kk@ukmuxgw7ubpe>
Date: Sat, 28 Jun 2025 20:08:57 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Yongbang Shi <shiyongbang@...wei.com>
Cc: xinliang.liu@...aro.org, tiantao6@...ilicon.com,
        maarten.lankhorst@...ux.intel.com, mripard@...nel.org,
        tzimmermann@...e.de, airlied@...il.com, daniel@...ll.ch,
        kong.kongxinwei@...ilicon.com, liangjian010@...wei.com,
        chenjianmin@...wei.com, lidongming5@...wei.com, libaihan@...wei.com,
        shenjian15@...wei.com, shaojijie@...wei.com,
        jani.nikula@...ux.intel.com, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 drm-dp 09/10] drm/hisilicon/hibmc: fix no showing
 problem with loading hibmc manually

On Fri, Jun 20, 2025 at 05:31:03PM +0800, Yongbang Shi wrote:
> From: Baihan Li <libaihan@...wei.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: 3c7623fb5bb6 ("drm/hisilicon/hibmc: Enable this hot plug detect of irq feature")
> Fixes: 94ee73ee3020 ("drm/hisilicon/hibmc: add dp hw moduel in hibmc driver")

So, which one had the issue?

> Signed-off-by: Baihan Li <libaihan@...wei.com>
> Signed-off-by: Yongbang Shi <shiyongbang@...wei.com>
> ---
> ChangeLog:
> v1 -> v2:
>   - fix the tag, suggested by Dmitry Baryshkov.
>   - separate the patch, suggested by Dmitry Baryshkov.
> ---
>  drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
> index 5b1f943b601c..edb7539d830e 100644
> --- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
> +++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
> @@ -178,6 +178,8 @@ int hibmc_dp_hw_init(struct hibmc_dp *dp)
>  	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);
>  	/* clock enable */
>  	writel(HIBMC_DP_CLK_EN, dp_dev->base + HIBMC_DP_DPTX_CLK_CTRL);
> -- 
> 2.33.0
> 

-- 
With best wishes
Dmitry