Hi Jocelyn Falempe, -----Original Message----- From: Jocelyn Falempe [mailto:jfalempe@xxxxxxxxxx] Sent: Wednesday, June 08, 2022 9:17 PM To: Kuo-Hsiang Chou <kuohsiang_chou@xxxxxxxxxxxxxx>; Thomas Zimmermann <tzimmermann@xxxxxxx>; airlied@xxxxxxxxxx; airlied@xxxxxxxx; daniel@xxxxxxxx; regressions@xxxxxxxxxxxxx Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx; stable@xxxxxxxxxxxxxxx; Luke Chen <luke_chen@xxxxxxxxxxxxxx>; Hungju Huang <hungju_huang@xxxxxxxxxxxxxx>; Charles Kuan <charles_kuan@xxxxxxxxxxxxxx> Subject: Re: [PATCH] drm/ast: Treat AST2600 like AST2500 in most places On 08/06/2022 10:09, Kuo-Hsiang Chou wrote: > Hi Thomas > > Thanks for your suggestions! > > I answer each revision inline that followed by [KH]:. Thanks for reviewing this. > > Regards, > > Kuo-Hsiang Chou > > -----Original Message----- > > From: Thomas Zimmermann [mailto:tzimmermann@xxxxxxx] > > Sent: Tuesday, June 07, 2022 8:03 PM > > To: airlied@xxxxxxxxxx; airlied@xxxxxxxx; daniel@xxxxxxxx; > jfalempe@xxxxxxxxxx; regressions@xxxxxxxxxxxxx; Kuo-Hsiang Chou > <kuohsiang_chou@xxxxxxxxxxxxxx> > > Subject: [PATCH] drm/ast: Treat AST2600 like AST2500 in most places > > Include AST2600 in most of the branches for AST2500. Thereby revert > most effects of commit f9bd00e0ea9d ("drm/ast: Create chip AST2600"). > > The AST2600 used to be treated like an AST2500, which at least gave > usable display output. After introducing AST2600 in the driver without > further updates, lots of functions take the wrong branches. > > Handling AST2600 in the AST2500 branches reverts back to the original > settings. The exception are cases where AST2600 meanwhile got its own > branch. > > [KH]: Based on CVE_2019_6260 item3, P2A is disallowed anymore. > > P2A (PCIe to AMBA) is a bridge that is able to revise any BMC registers. > > Yes, P2A is dangerous on security issue, because Host open a backdoor > and someone malicious SW/APP will be easy to take control of BMC. > > Therefore, P2A is disabled forever. > > Now, return to this patch, there is no need to add AST2600 condition > on the P2A flow. > [snip] > > [KH]: Yes, the patch is "drm/ast: Create threshold values for AST2600" > that is the root cause of whites lines on AST2600 > > commit > > > bcc77411e8a65929655cef7b63a36000724cdc4b > <https://cgit.freedesktop.org/drm/drm/commit/?id=bcc77411e8a65929655ce > f7b63a36000724cdc4b> (patch > <https://cgit.freedesktop.org/drm/drm/patch/?id=bcc77411e8a65929655cef > 7b63a36000724cdc4b>) > So basically this commit should be enough to fix the white lines and flickering with VGA output on AST2600 ? [KH]: Yes. You are welcome to tell me something if you consider there is other strange issue. Thanks for your efforts on drm/ast project! Regards, Kuo-Hsiang Chou I will try to have it tested, and if it's good, we may want to have it on stable kernel. Best regards, -- Jocelyn
