Re: [Intel-gfx] [PATCH 1/2] drm/i915/gt: Add GT oriented dmesg output

[Michal Wajdeczko <michal.wajdeczko@intel.com>]

On 10.11.2022 10:55, Tvrtko Ursulin wrote:
> 
> On 09/11/2022 19:57, Michal Wajdeczko wrote:
> 
> [snip]
> 
>>> Is it really a problem to merge this patch now to get the process
>>> started? And other sub-components get updated as and when people get the
>>> time to do them? You could maybe even help rather than posting
>>> completely conflicting patch sets that basically duplicate all the
>>> effort for no actual benefit.
>>
>> Instead of merging this patch now, oriented on GT only, I would rather
>> wait until we discuss and plan solution for the all sub-components.
> 
> Yes, agreed.
> 
>> Once that's done (with agreement on naming and output) we can start
>> converting exiting messages.
>>
>> My proposal would be:
>>   - use wrappers per component
> 
> This is passable to me but Jani has raised a concern on IRC that it
> leads to a lot of macro duplication. Which is I think a valid point, but
> which does not have a completely nice solution. Best I heard so far was
> a suggestion from Joonas to add just a single component formatter macro
> and use the existing drm_xxx helpers.
> 
>>   - use lower case names
> 
> I prefer this as well. Even though usual argument is for macros to be
> upper case, I find the improved readability of lower case trumps that.
> 
>>   - don't add colon
> 
> Not sure, when I look at it below it looks a bit not structured enough
> without the colon, but maybe it is just me.
> 
>> #define i915_xxx(_i915, _fmt, ...) \
>>     drm_xxx(&(_i915)->drm, _fmt, ##__VA_ARGS__)
>>
>> #define gt_xxx(_gt, _fmt, ...) \
>>     i915_xxx((_gt)->i915, "GT%u " _fmt, (_gt)->info.id, ..
>>
>> #define guc_xxx(_guc, _fmt, ...) \
>>     gt_xxx(guc_to_gt(_guc), "GuC " _fmt, ..
>>
>> #define ct_xxx(_ct, _fmt, ...) \
>>     guc_xxx(ct_to_guc(_ct), "CTB " _fmt, ..
>>
>> where
>>     xxx = { err, warn, notice, info, dbg }
>>
>> and then for calls like:
>>
>>     i915_err(i915, "Foo failed (%pe)\n", ERR_PTR(err));
>>       gt_err(gt,   "Foo failed (%pe)\n", ERR_PTR(err));
>>      guc_err(guc,  "Foo failed (%pe)\n", ERR_PTR(err));
>>       ct_err(ct,   "Foo failed (%pe)\n", ERR_PTR(err));
> 
> So the macro idea would be like this:
> 
>   drm_err(I915_LOG("Foo failed (%pe)\n", i915), ERR_PTR(err));
>   drm_err(GT_LOG("Foo failed (%pe)\n", gt), ERR_PTR(err));
>   drm_err(GUC_LOG("Foo failed (%pe)\n", guc), ERR_PTR(err));
>   drm_err(CT_LOG("Foo failed (%pe)\n", ct), ERR_PTR(err));
> 
> Each component would just need to define a single macro and not have to
> duplicate all the err, info, warn, notice, ratelimited, once, whatever
> versions. Which is a benefit but it's a quite a bit uglier to read in
> the code.

If there is a choice between having ugly code all over the place and few
more lines with helpers then without any doubts I would pick the latter.

And this seems to be option already used elsewhere, see:

#define dev_err(dev, fmt, ...) \
	dev_printk_index_wrap ...

#define pci_err(pdev, fmt, arg...) \
	dev_err(&(pdev)->dev, fmt, ##arg)

#define drm_err(drm, fmt, ...) \
	__drm_printk((drm), err,, "*ERROR* " fmt, ##__VA_ARGS__)

#define drbd_err(obj, fmt, args...) \
	drbd_printk(KERN_ERR, obj, fmt, ## args)

#define ch7006_err(client, format, ...) \
	dev_err(&client->dev, format, __VA_ARGS__)

#define mthca_err(mdev, format, arg...) \
	dev_err(&mdev->pdev->dev, format, ## arg)

#define ctx_err(ctx, fmt, arg...) \
	cal_err((ctx)->cal, "ctx%u: " fmt, (ctx)->dma_ctx, ##arg)

#define mlx4_err(mdev, format, ...) \
	dev_err(&(mdev)->persist->pdev->dev, format, ##__VA_ARGS__)

...

Michal


[1]
https://elixir.bootlin.com/linux/v6.1-rc4/source/include/linux/dev_printk.h#L143

[2]
https://elixir.bootlin.com/linux/v6.1-rc4/source/include/linux/pci.h#L2485

[3]
https://elixir.bootlin.com/linux/v6.1-rc4/source/include/drm/drm_print.h#L468

[4]
https://elixir.bootlin.com/linux/v6.1-rc4/source/drivers/block/drbd/drbd_int.h#L113

[5]
https://elixir.bootlin.com/linux/v6.1-rc4/source/drivers/gpu/drm/i2c/ch7006_priv.h#L139

[6]
https://elixir.bootlin.com/linux/v6.1-rc4/source/drivers/infiniband/hw/mthca/mthca_dev.h#L377

[7]
https://elixir.bootlin.com/linux/v6.1-rc4/source/drivers/media/platform/ti/cal/cal.h#L279

[8]
https://elixir.bootlin.com/linux/v6.1-rc4/source/drivers/net/ethernet/mellanox/mlx4/mlx4.h#L225

> 
> Perhaps macro could be called something other than XX_LOG to make it
> more readable, don't know.
> 
> Regards,
> 
> Tvrtko