linux-kernel - Re: [PATCH 2/2] drm/msm/dpu: don't play tricks with debug macros

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Message-ID: <46487222-6818-b0bf-e5cc-2310d62b5fe6@quicinc.com>
Date: Tue, 9 Jul 2024 12:38:00 -0700
From: Abhinav Kumar <quic_abhinavk@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Rob Clark
	<robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        Marijn Suijten
	<marijn.suijten@...ainline.org>,
        David Airlie <airlied@...il.com>, Daniel
 Vetter <daniel@...ll.ch>,
        Jordan Crouse <jordan@...micpenguin.net>,
        Chandan
 Uddaraju <chandanu@...eaurora.org>,
        Rajesh Yadav <ryadav@...eaurora.org>,
        Sravanthi Kollukuduru <skolluku@...eaurora.org>,
        Archit Taneja
	<architt@...eaurora.org>
CC: <linux-arm-msm@...r.kernel.org>, <dri-devel@...ts.freedesktop.org>,
        <freedreno@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
        Jeykumar
 Sankaran <jsanka@...eaurora.org>
Subject: Re: [PATCH 2/2] drm/msm/dpu: don't play tricks with debug macros



On 7/9/2024 6:48 AM, Dmitry Baryshkov wrote:
> DPU debugging macros need to be converted to a proper drm_debug_*
> macros, however this is a going an intrusive patch, not suitable for a
> fix. Wire DPU_DEBUG and DPU_DEBUG_DRIVER to always use DRM_DEBUG_DRIVER
> to make sure that DPU debugging messages always end up in the drm debug
> messages and are controlled via the usual drm.debug mask.
> 

These macros have been deprecated, is this waht you meant by the 
conversion to proper drm_debug_*?

/* NOTE: this is deprecated in favor of drm_dbg(NULL, ...). */
#define DRM_DEBUG_DRIVER(fmt, ...)                                      \
         __drm_dbg(DRM_UT_DRIVER, fmt, ##__VA_ARGS__)

I think all that this macro was doing was to have appropriate DRM_UT_* 
macros enabled before calling the corresponding DRM_DEBUG_* macros. But 
I think what was incorrect here is for DPU_DEBUG, we could have used 
DRM_UT_CORE instead of DRM_UT_KMS.

And DRM_DEBUG_DRIVER should have been used instead of DRM_ERROR.

Was this causing the issue of the prints not getting enabled?

> Fixes: 25fdd5933e4c ("drm/msm: Add SDM845 DPU support")
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> ---
>   drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h | 14 ++------------
>   1 file changed, 2 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
> index e2adc937ea63..935ff6fd172c 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
> @@ -31,24 +31,14 @@
>    * @fmt: Pointer to format string
>    */
>   #define DPU_DEBUG(fmt, ...)                                                \
> -	do {                                                               \
> -		if (drm_debug_enabled(DRM_UT_KMS))                         \
> -			DRM_DEBUG(fmt, ##__VA_ARGS__); \
> -		else                                                       \
> -			pr_debug(fmt, ##__VA_ARGS__);                      \
> -	} while (0)
> +	DRM_DEBUG_DRIVER(fmt, ##__VA_ARGS__)
>   
>   /**
>    * DPU_DEBUG_DRIVER - macro for hardware driver logging
>    * @fmt: Pointer to format string
>    */
>   #define DPU_DEBUG_DRIVER(fmt, ...)                                         \
> -	do {                                                               \
> -		if (drm_debug_enabled(DRM_UT_DRIVER))                      \
> -			DRM_ERROR(fmt, ##__VA_ARGS__); \
> -		else                                                       \
> -			pr_debug(fmt, ##__VA_ARGS__);                      \
> -	} while (0)
> +	DRM_DEBUG_DRIVER(fmt, ##__VA_ARGS__)
>   
>   #define DPU_ERROR(fmt, ...) pr_err("[dpu error]" fmt, ##__VA_ARGS__)
>   #define DPU_ERROR_RATELIMITED(fmt, ...) pr_err_ratelimited("[dpu error]" fmt, ##__VA_ARGS__)
>