linux-kernel - Re: [PATCH v7 1/7] drm/print: Fix and add support for NULL as first argument in drm

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Message-ID: <18693900367.2ce71ba5548919.6872574648582795181@siddh.me>
Date:   Mon, 27 Feb 2023 21:18:54 +0530
From:   Siddh Raman Pant <code@...dh.me>
To:     "Jani Nikula" <jani.nikula@...ux.intel.com>
Cc:     "maarten lankhorst" <maarten.lankhorst@...ux.intel.com>,
        "maxime ripard" <mripard@...nel.org>,
        "thomas zimmermann" <tzimmermann@...e.de>,
        "david airlie" <airlied@...il.com>,
        "daniel vetter" <daniel@...ll.ch>,
        "jim cromie" <jim.cromie@...il.com>,
        "sam ravnborg" <sam@...nborg.org>,
        "linux-kernel" <linux-kernel@...r.kernel.org>,
        "dri-devel" <dri-devel@...ts.freedesktop.org>
Subject: Re: [PATCH v7 1/7] drm/print: Fix and add support for NULL as first
 argument in drm_* macros

On Mon, 27 Feb 2023 15:13:21 +0530, Jani Nikula wrote:
> First of all, that's two distinct changes in one patch. The subject says
> one thing, but it's really two.

Sorry, my bad.

> But the main question is, do we *really* want to let callers pass either
> struct drm_device * or struct device *? It will be type safe with
> generics, but if it's okay to use either, people *will* use either. The
> call sites will end up being a mixture of both. You can't control it. It
> will be very tedious if you ever want to revert that decision.
> 
> Do we want to promote a style where you can pass either? To me, in C
> context, it seems awfully sloppy and confusing rather than convenient.
> 
> I'd argue the struct mipi_dsi_host stuff should use dev_* calls
> directly, as it's more of a special case, rather than allow struct
> device * in drm_* logging macros.

I agree. I thought direct dev_* calls would not be ideal, as there is a
TODO to move away from that, and also incorrectly expected to have more
such dev ptr problems. But on a second thought, you are correct.

Should I post a new patch, with using __drm_dev_ptr instead and
removing the __get_dev_ptr generic macro, and using dev_* in
drm_mipi_dsi.c as `dev_err(dev, "*ERROR* [drm] <msg>", ...);`?

> BR,
> Jani.

Thanks,
Siddh