From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Sui Jingfeng <sui.jingfeng@linux.dev>
Cc: Neil Armstrong <neil.armstrong@linaro.org>,
Randy Dunlap <rdunlap@infradead.org>,
dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
Jessica Zhang <quic_jesszhan@quicinc.com>,
Sam Ravnborg <sam@ravnborg.org>,
Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
Maxime Ripard <mripard@kernel.org>,
Thomas Zimmermann <tzimmermann@suse.de>,
David Airlie <airlied@gmail.com>, Daniel Vetter <daniel@ffwll.ch>
Subject: Re: [v1,1/3] drm/panel: ili9341: Correct use of device property APIs
Date: Thu, 25 Apr 2024 22:10:00 +0300 [thread overview]
Message-ID: <ZiqqiAztCaiAgI8e@smile.fi.intel.com> (raw)
In-Reply-To: <c2d41916-0b6c-43b5-98eb-514eb0511f84@linux.dev>
On Fri, Apr 26, 2024 at 02:08:16AM +0800, Sui Jingfeng wrote:
> On 2024/4/25 22:26, Andy Shevchenko wrote:
> > It seems driver missed the point of proper use of device property APIs.
> > Correct this by updating headers and calls respectively.
>
> You are using the 'seems' here exactly saying that you are not 100% sure.
>
> Please allow me to tell you the truth: This patch again has ZERO effect.
> It fix nothing. And this patch is has the risks to be wrong.
Huh?! Really, stop commenting the stuff you do not understand.
> Simple because the "ili9341_probe() ---> ili9341_dbi_prob()" code path
> is DT dependent.
>
> First of all, the devm_of_find_backlight() is called in ili9341_dbi_probe()
> under *non-DT* environment, devm_of_find_backlight() is just a just a
> no-op and will return NULL. NULL is not an error code, so ili9341_dbi_probe()
> won't rage quit. But the several side effect is that the backlight will
> NOT works at all.
Is it a problem?
> It is actually considered as fatal bug for *panels* if the backlight of
> it is not light up, at least the brightness of *won't* be able to adjust.
> What's worse, if there is no sane platform setup code at the firmware
> or boot loader stage to set a proper initial state. The screen is complete
> dark. Even though the itself panel is refreshing framebuffers, it can not
> be seen by human's eye. Simple because of no backlight.
Can you imagine that I may have different hardware that considered
this is non-fatal error?
> Second, the ili9341_dbi_probe() requires additional device properties to
> be able to works very well on the rotation screen case. See the calling
> of "device_property_read_u32(dev, "rotation", &rotation)" in
> ili9341_dbi_probe() function.
Yes, exactly, and how does it object the purpose of this patch?
> Combine with those two factors, it is actually can conclude that the
> panel-ilitek-ili9394 driver has the *implicit* dependency on 'OF'.
> Removing the 'OF' dependency from its Kconfig just trigger the
> leakage of such risks.
What?!
> My software node related patches can help to reduce part of the potential
> risks, but it still need some extra work. And it is not landed yet.
Your patch has nothing to do with this series.
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2024-04-25 19:10 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-25 14:26 [PATCH v1 0/3] drm/panel: ili9341: Obvious fixes Andy Shevchenko
2024-04-25 14:26 ` [PATCH v1 1/3] drm/panel: ili9341: Correct use of device property APIs Andy Shevchenko
2024-04-25 16:00 ` Neil Armstrong
2024-04-25 18:08 ` [v1,1/3] " Sui Jingfeng
2024-04-25 18:53 ` Sui Jingfeng
2024-04-25 19:12 ` Andy Shevchenko
2024-04-25 21:13 ` Sui Jingfeng
2024-04-30 14:13 ` Andy Shevchenko
2024-04-30 16:27 ` Sui Jingfeng
2024-05-02 8:32 ` Andy Shevchenko
2024-05-02 16:25 ` Sui Jingfeng
2024-05-02 17:28 ` Andy Shevchenko
2024-05-03 4:57 ` Sui Jingfeng
2024-05-03 15:46 ` Andy Shevchenko
2024-04-25 19:10 ` Andy Shevchenko [this message]
2024-04-25 20:43 ` Sui Jingfeng
2024-04-25 21:27 ` Sui Jingfeng
2024-04-26 6:23 ` Maxime Ripard
2024-04-27 5:57 ` Sui Jingfeng
2024-04-29 11:55 ` Maxime Ripard
2024-04-29 16:54 ` Sui Jingfeng
2024-04-30 9:34 ` Maxime Ripard
2024-05-02 7:34 ` Neil Armstrong
2024-05-02 8:33 ` Andy Shevchenko
2024-05-02 17:28 ` Sui Jingfeng
2024-05-02 17:38 ` Andy Shevchenko
2024-04-30 14:32 ` Andy Shevchenko
2024-04-30 17:24 ` Sui Jingfeng
2024-04-30 10:19 ` [PATCH v1 1/3] " Dmitry Baryshkov
2024-04-25 14:26 ` [PATCH v1 2/3] drm/panel: ili9341: Respect deferred probe Andy Shevchenko
2024-04-25 16:00 ` Neil Armstrong
2024-04-30 10:21 ` Dmitry Baryshkov
2024-04-30 16:50 ` [v1,2/3] " Sui Jingfeng
2024-04-25 14:26 ` [PATCH v1 3/3] drm/panel: ili9341: Use predefined error codes Andy Shevchenko
2024-04-25 16:00 ` Neil Armstrong
2024-04-30 16:54 ` [v1,3/3] " Sui Jingfeng
2024-04-25 15:08 ` [PATCH v1 0/3] drm/panel: ili9341: Obvious fixes Andy Shevchenko
2024-05-02 7:43 ` Neil Armstrong
2024-05-02 8:33 ` Andy Shevchenko
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