Re: [PATCH] drm/sysfb: ofdrm: Fix is_avivo() constant comparison bug

[Thomas Zimmermann <tzimmermann@suse.de>]

Hi

Am 24.07.26 um 11:41 schrieb oushixiong1025@163.com:
> From: Shixiong Ou <oushixiong@kylinos.cn>
>
> The is_avivo() function has a logic error where it compares a constant
> to another constant instead of checking the device parameter:
>
>    (PCI_VENDOR_ID_ATI_R600 >= 0x9400)
>
> However, according to the code comment and the OFDRM_MODEL_AVIVO
> definition ("ATI R5xx"), this function is intended to match only R5xx
> cards (device IDs 0x7100-0x7800), not R6xx or later. The second
> condition checking for R600 is erroneous and should be removed.
>
> Signed-off-by: Shixiong Ou <oushixiong@kylinos.cn>
> ---
>   drivers/gpu/drm/sysfb/ofdrm.c | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/sysfb/ofdrm.c b/drivers/gpu/drm/sysfb/ofdrm.c
> index a6dc34b9ec0f..ea1db1cfe3ed 100644
> --- a/drivers/gpu/drm/sysfb/ofdrm.c
> +++ b/drivers/gpu/drm/sysfb/ofdrm.c
> @@ -238,8 +238,7 @@ static bool is_avivo(u32 vendor, u32 device)
>   {
>   	/* This will match most R5xx */
>   	return (vendor == PCI_VENDOR_ID_ATI) &&
> -	       ((device >= PCI_VENDOR_ID_ATI_R520 && device < 0x7800) ||
> -		(PCI_VENDOR_ID_ATI_R600 >= 0x9400));

I tried to match exactly this: 
https://elixir.bootlin.com/linux/v7.1.4/source/drivers/video/fbdev/offb.c#L365

IDK if that works in practice, but I don't dare changing it without a 
concrete bug report.

Best regards
Thomas

> +	       (device >= PCI_VENDOR_ID_ATI_R520 && device < 0x7800);
>   }
>   
>   static enum ofdrm_model display_get_model_of(struct drm_device *dev, struct device_node *of_node)

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, (HRB 36809, AG Nürnberg)