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

[Nicolas Ferre]

On 09/11/2023 at 10:55, Helge Deller wrote:
> On 11/9/23 07:24, Uwe Kleine-König wrote:
>> Hello,
>>
>> On Wed, Nov 08, 2023 at 10:57:00PM +0100, Helge Deller wrote:
>>> On 11/8/23 22:52, Uwe Kleine-König wrote:
>>>> 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.
>>
>> If you say so that's good. I grepped a bit around and didn't find a
>> place where a copy is made. But that's probably me and I'll consider the
>> case closed.
> 
> It's not directly obvious, but the copy happens in the line you pointed
> out previously.
> 
> In include/linux/fb.h:
> 
> struct fb_info {
> ...
>           struct fb_var_screeninfo var;   /* Current var */
>           struct fb_fix_screeninfo fix;   /* Current fix */
> 
> so, "fb_info.fix" is a struct, and not a pointer.
> 
> In drivers/video/fbdev/atmel_lcdfb.c:
> static int atmel_lcdfb_probe(struct platform_device *pdev)
> {
> ...
>           info->fix = atmel_lcdfb_fix;  //  (line 1065)
> 
> this becomes effectively a:
>          memcpy(&info->fix, &atmel_lcdfb_fix, sizeof(struct fb_fix_screeninfo));
> 
> so, the compiler copies the "__initconst" data over to the info->fix struct.

Helge, Uwe and Nathan,

Thanks a lot for making this move, patch and detailed explanation.

Best regards,
   Nicolas