linux-kernel - Re: [3/5] drm/komeda: Optionally dump DRM state on interrupts

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Message-ID: <20191101071659.GA30189@jamwan02-TSP300>
Date:   Fri, 1 Nov 2019 07:17:06 +0000
From:   "james qian wang (Arm Technology China)" <james.qian.wang@....com>
To:     Mihail Atanassov <Mihail.Atanassov@....com>
CC:     "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        David Airlie <airlied@...ux.ie>,
        Liviu Dudau <Liviu.Dudau@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Lowry Li (Arm Technology China)" <Lowry.Li@....com>,
        nd <nd@....com>, Sean Paul <sean@...rly.run>
Subject: Re: [3/5] drm/komeda: Optionally dump DRM state on interrupts

On Mon, Oct 21, 2019 at 04:47:24PM +0000, Mihail Atanassov wrote:
> It's potentially useful information when diagnosing error/warn IRQs, so
> dump it to dmesg with a drm_info_printer. Hide this extra debug dumping
> behind another komeda_dev->err_verbosity bit.
> 
> Note that there's not much sense in dumping it for INFO events,
> since the VSYNC event will swamp the log.
> 
> Signed-off-by: Mihail Atanassov <mihail.atanassov@....com>

Reviewed-by: James Qian Wang (Arm Technology China) <james.qian.wang@....com>
> ---
>  drivers/gpu/drm/arm/display/komeda/komeda_dev.h   | 5 ++++-
>  drivers/gpu/drm/arm/display/komeda/komeda_event.c | 8 +++++++-
>  2 files changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_dev.h b/drivers/gpu/drm/arm/display/komeda/komeda_dev.h
> index 831c375180f8..4809000c1efb 100644
> --- a/drivers/gpu/drm/arm/display/komeda/komeda_dev.h
> +++ b/drivers/gpu/drm/arm/display/komeda/komeda_dev.h
> @@ -205,11 +205,14 @@ struct komeda_dev {
>  	/**
>  	 * @err_verbosity: bitmask for how much extra info to print on error
>  	 *
> -	 * See KOMEDA_DEV_* macros for details.
> +	 * See KOMEDA_DEV_* macros for details. Low byte contains the debug
> +	 * level categories, the high byte contains extra debug options.
>  	 */
>  	u16 err_verbosity;
>  	/* Print a single line per error per frame with error events. */
>  #define KOMEDA_DEV_PRINT_ERR_EVENTS BIT(0)
> +	/* Dump DRM state on an error or warning event. */
> +#define KOMEDA_DEV_PRINT_DUMP_STATE_ON_EVENT BIT(8)
>  };
>  
>  static inline bool
> diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_event.c b/drivers/gpu/drm/arm/display/komeda/komeda_event.c
> index 575ed4df74ed..5da61e7d75d5 100644
> --- a/drivers/gpu/drm/arm/display/komeda/komeda_event.c
> +++ b/drivers/gpu/drm/arm/display/komeda/komeda_event.c
> @@ -4,6 +4,7 @@
>   * Author: James.Qian.Wang <james.qian.wang@....com>
>   *
>   */
> +#include <drm/drm_atomic.h>
>  #include <drm/drm_print.h>
>  
>  #include "komeda_dev.h"
> @@ -113,6 +114,7 @@ void komeda_print_events(struct komeda_events *evts, struct drm_device *dev)
>  	static bool en_print = true;
>  	struct komeda_dev *mdev = dev->dev_private;
>  	u16 const err_verbosity = mdev->err_verbosity;
> +	u64 evts_mask = evts->global | evts->pipes[0] | evts->pipes[1];
>  
>  	/* reduce the same msg print, only print the first evt for one frame */
>  	if (evts->global || is_new_frame(evts))
> @@ -123,9 +125,10 @@ void komeda_print_events(struct komeda_events *evts, struct drm_device *dev)
>  	if (err_verbosity & KOMEDA_DEV_PRINT_ERR_EVENTS)
>  		print_evts |= KOMEDA_ERR_EVENTS;
>  
> -	if ((evts->global | evts->pipes[0] | evts->pipes[1]) & print_evts) {
> +	if (evts_mask & print_evts) {
>  		char msg[256];
>  		struct komeda_str str;
> +		struct drm_printer p = drm_info_printer(dev->dev);
>  
>  		str.str = msg;
>  		str.sz  = sizeof(msg);
> @@ -139,6 +142,9 @@ void komeda_print_events(struct komeda_events *evts, struct drm_device *dev)
>  		evt_str(&str, evts->pipes[1]);
>  
>  		DRM_ERROR("err detect: %s\n", msg);
> +		if ((err_verbosity & KOMEDA_DEV_PRINT_DUMP_STATE_ON_EVENT)
> +		    && (evts_mask & (KOMEDA_ERR_EVENTS | KOMEDA_WARN_EVENTS)))
> +			drm_state_dump(dev, &p);
>  
>  		en_print = false;
>  	}