Re: [PATCH v3 6/7] venus: Make debug infrastructure more flexible - Greg Kroah-Hartman

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Stanimir Varbanov <stanimir.varbanov@linaro.org>
Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-media@vger.kernel.org, linux-arm-msm@vger.kernel.org,
	linux-btrfs@vger.kernel.org, linux-acpi@vger.kernel.org,
	netdev@vger.kernel.org, Joe Perches <joe@perches.com>,
	Jason Baron <jbaron@akamai.com>
Subject: Re: [PATCH v3 6/7] venus: Make debug infrastructure more flexible
Date: Tue, 9 Jun 2020 13:14:14 +0200	[thread overview]
Message-ID: <20200609111414.GC780233@kroah.com> (raw)
In-Reply-To: <20200609104604.1594-7-stanimir.varbanov@linaro.org>

On Tue, Jun 09, 2020 at 01:46:03PM +0300, Stanimir Varbanov wrote:
> Here we introduce few debug macros with levels (low, medium and
> high) and debug macro for firmware. Enabling the particular level
> will be done by dynamic debug with levels.
> 
> For example to enable debug messages with low level:
> echo 'module venus_dec level 0x01 +p' > debugfs/dynamic_debug/control
> 
> If you want to enable all levels:
> echo 'module venus_dec level 0x07 +p' > debugfs/dynamic_debug/control
> 
> All the features which dynamic debugging provide are preserved.
> 
> And finaly all dev_dbg are translated to VDBGX with appropriate
> debug levels.
> 
> Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
> ---
>  drivers/media/platform/qcom/venus/core.h      |  5 ++
>  drivers/media/platform/qcom/venus/helpers.c   |  2 +-
>  drivers/media/platform/qcom/venus/hfi_msgs.c  | 30 ++++-----
>  drivers/media/platform/qcom/venus/hfi_venus.c | 20 ++++--
>  .../media/platform/qcom/venus/pm_helpers.c    |  3 +-
>  drivers/media/platform/qcom/venus/vdec.c      | 63 +++++++++++++++++--
>  drivers/media/platform/qcom/venus/venc.c      |  4 ++
>  7 files changed, 96 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/media/platform/qcom/venus/core.h b/drivers/media/platform/qcom/venus/core.h
> index b48782f9aa95..63eabf5ff96d 100644
> --- a/drivers/media/platform/qcom/venus/core.h
> +++ b/drivers/media/platform/qcom/venus/core.h
> @@ -15,6 +15,11 @@
>  #include "dbgfs.h"
>  #include "hfi.h"
>  
> +#define VDBGL(fmt, args...)	pr_debug_level(0x01, fmt, ##args)
> +#define VDBGM(fmt, args...)	pr_debug_level(0x02, fmt, ##args)
> +#define VDBGH(fmt, args...)	pr_debug_level(0x04, fmt, ##args)
> +#define VDBGFW(fmt, args...)	pr_debug_level(0x08, fmt, ##args)
> +
>  #define VIDC_CLKS_NUM_MAX		4
>  #define VIDC_VCODEC_CLKS_NUM_MAX	2
>  #define VIDC_PMDOMAINS_NUM_MAX		3
> diff --git a/drivers/media/platform/qcom/venus/helpers.c b/drivers/media/platform/qcom/venus/helpers.c
> index 0143af7822b2..115a9a2af1d6 100644
> --- a/drivers/media/platform/qcom/venus/helpers.c
> +++ b/drivers/media/platform/qcom/venus/helpers.c
> @@ -396,7 +396,7 @@ put_ts_metadata(struct venus_inst *inst, struct vb2_v4l2_buffer *vbuf)
>  	}
>  
>  	if (slot == -1) {
> -		dev_dbg(inst->core->dev, "%s: no free slot\n", __func__);
> +		VDBGH("no free slot for timestamp\n");

So you just lost the information that dev_dbg() gave you with regards to
the device/driver/instance creating that message?

Ick, no, don't do that.

And why is this driver somehow "special" compared to all the rest of
the kernel?  Why is the current dev_dbg() control not sufficient that
you need to change the core for just this tiny thing?

thanks,

greg k-h