linux-kernel - Re: [PATCH v2 01/12] drm/msm/dp: fix HPD state status bit shift value

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Message-ID: <200ee7f2-ac66-4619-9401-220dc578f8d4@oss.qualcomm.com>
Date: Sat, 9 Aug 2025 03:38:24 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Jessica Zhang <jessica.zhang@....qualcomm.com>,
        Rob Clark <robin.clark@....qualcomm.com>,
        Abhinav Kumar <abhinav.kumar@...ux.dev>,
        Dmitry Baryshkov
 <lumag@...nel.org>, Sean Paul <sean@...rly.run>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
        Kuogee Hsieh <quic_khsieh@...cinc.com>
Cc: linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Yongxing Mou <quic_yongmou@...cinc.com>
Subject: Re: [PATCH v2 01/12] drm/msm/dp: fix HPD state status bit shift value

On 09/08/2025 03:35, Jessica Zhang wrote:
> The HPD state status is the last 3 bits, not 4 bits of the
> HPD_INT_STATUS register.

Then the mask is incorrect too. Also, I'd suggest using 'most 
significant' instead of 'last'. The latter one might be confusing.

> 
> Fix the bit shift macro so that the correct bits are returned in
> msm_dp_aux_is_link_connected().
> 
> Fixes: 19e52bcb27c2 ("drm/msm/dp: return correct connection status after suspend")
> Signed-off-by: Jessica Zhang <jessica.zhang@....qualcomm.com>
> ---
>   drivers/gpu/drm/msm/dp/dp_reg.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/msm/dp/dp_reg.h b/drivers/gpu/drm/msm/dp/dp_reg.h
> index 7c44d4e2cf13..b851efc132ea 100644
> --- a/drivers/gpu/drm/msm/dp/dp_reg.h
> +++ b/drivers/gpu/drm/msm/dp/dp_reg.h
> @@ -69,7 +69,7 @@
>   #define DP_DP_HPD_REPLUG_INT_ACK		(0x00000004)
>   #define DP_DP_HPD_UNPLUG_INT_ACK		(0x00000008)
>   #define DP_DP_HPD_STATE_STATUS_BITS_MASK	(0x0000000F)
> -#define DP_DP_HPD_STATE_STATUS_BITS_SHIFT	(0x1C)
> +#define DP_DP_HPD_STATE_STATUS_BITS_SHIFT	(0x1D)
>   
>   #define REG_DP_DP_HPD_INT_MASK			(0x0000000C)
>   #define DP_DP_HPD_PLUG_INT_MASK			(0x00000001)
> 


-- 
With best wishes
Dmitry