Re: [PATCH 02/22] fb: atmel_lcdfb: Stop using platform_driver_probe()

From: Helge Deller <deller@gmx.de>
To: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Cc: linux-fbdev@vger.kernel.org, llvm@lists.linux.dev,
	Alexandre Belloni <alexandre.belloni@bootlin.com>,
	dri-devel@lists.freedesktop.org,
	Claudiu Beznea <claudiu.beznea@tuxon.dev>,
	Nathan Chancellor <nathan@kernel.org>,
	kernel@pengutronix.de, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 02/22] fb: atmel_lcdfb: Stop using platform_driver_probe()
Date: Wed, 8 Nov 2023 22:57:00 +0100	[thread overview]
Message-ID: <656080fb-7d10-47ec-bdeb-a099ceee99bf@gmx.de> (raw)
In-Reply-To: <20231108215220.3iw5sydxad32gufj@pengutronix.de>

On 11/8/23 22:52, Uwe Kleine-König wrote:
> On Wed, Nov 08, 2023 at 10:24:09PM +0100, Helge Deller wrote:
>> On 11/8/23 22:00, Uwe Kleine-König wrote:
>>> On Wed, Nov 08, 2023 at 11:48:05AM -0700, Nathan Chancellor wrote:
>>>> diff --git a/drivers/video/fbdev/atmel_lcdfb.c b/drivers/video/fbdev/atmel_lcdfb.c
>>>> index 88c75ae7d315..9e391e5eaf9d 100644
>>>> --- a/drivers/video/fbdev/atmel_lcdfb.c
>>>> +++ b/drivers/video/fbdev/atmel_lcdfb.c
>>>> @@ -220,7 +220,7 @@ static inline void atmel_lcdfb_power_control(struct atmel_lcdfb_info *sinfo, int
>>>>    	}
>>>>    }
>>>>
>>>> -static const struct fb_fix_screeninfo atmel_lcdfb_fix __initconst = {
>>>> +static const struct fb_fix_screeninfo atmel_lcdfb_fix = {
>>>>    	.type		= FB_TYPE_PACKED_PIXELS,
>>>>    	.visual		= FB_VISUAL_TRUECOLOR,
>>>>    	.xpanstep	= 0,
>>>
>>> I wonder if this was broken already before my patch. atmel_lcdfb_probe()
>>> does
>>>
>>> 	info->fix = atmel_lcdfb_fix;
>>>
>>> and unless I miss something (this is well possible) that is used e.g. in
>>> atmel_lcdfb_set_par() -> atmel_lcdfb_update_dma(). So atmel_lcdfb_fix
>>> should better not live in .init memory?! Someone with more knowledge
>>> about fbdev might want to take a look and decide if this justifies a
>>> separate fix that should then be backported to stable, too?!
>>
>> I don't think a backport this is necessary.
>> The "__initconst" atmel_lcdfb_fix struct was only copied in the
>> "__init" atmel_lcdfb_probe() function.
>> So, both were dropped at the same time in older kernels.
>
> But info and so info->fix live longer than the probe function, don't
> they?

Yes, they do.
But AFAICS info->fix contains a *copy* of the initial atmel_lcdfb_fix struct
(and not a pointer to it). So that should be ok.

Helge

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