Re: [PATCH v2] drm/ast: Fix ARM compatibility

[Jammy Huang <jammy_huang@xxxxxxxxxxxxxx>]

Hi Thomas,

Thanks for help. I will update a new patch per your comments

On 2023/4/20 下午 04:57, Thomas Zimmermann wrote:
> Hi
>
> Am 20.04.23 um 10:09 schrieb Jammy Huang:
> > ARM architecture only has 'memory', so all devices are accessed by
> > MMIO if possible.
> >
> > Signed-off-by: Jammy Huang <jammy_huang@xxxxxxxxxxxxxx>
> > ---
> >   v2 changes:
> >    - Use MMIO after AST2500 which enable MMIO by default.
> > ---
> >   drivers/gpu/drm/ast/ast_main.c | 9 +++++----
> >   1 file changed, 5 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/ast/ast_main.c 
> > b/drivers/gpu/drm/ast/ast_main.c
> > index f83ce77127cb..d384e810fa4d 100644
> > --- a/drivers/gpu/drm/ast/ast_main.c
> > +++ b/drivers/gpu/drm/ast/ast_main.c
> > @@ -425,11 +425,12 @@ struct ast_private *ast_device_create(const 
> > struct drm_driver *drv,
> >           return ERR_PTR(-EIO);
> >         /*
> > -     * If we don't have IO space at all, use MMIO now and
> > -     * assume the chip has MMIO enabled by default (rev 0x20
> > -     * and higher).
> > +     * After AST2500, MMIO is enabled by default, and it should be 
> > adapted
>
> By 'adapted', you mean 'adopted'?
>
> Apart from that:
>
> Reviewed-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
>
> I also ran this patch on an AST2100, which still works as before.
>
> Best regards
> Thomas
>
> > +     * to be compatible with Arm.
> >        */
> > -    if (!(pci_resource_flags(pdev, 2) & IORESOURCE_IO)) {
> > +    if (pdev->revision >= 0x40) {
> > +        ast->ioregs = ast->regs + AST_IO_MM_OFFSET;
> > +    } else if (!(pci_resource_flags(pdev, 2) & IORESOURCE_IO)) {
> >           drm_info(dev, "platform has no IO space, trying MMIO\n");
> >           ast->ioregs = ast->regs + AST_IO_MM_OFFSET;
> >       }
> >
> > base-commit: e62252bc55b6d4eddc6c2bdbf95a448180d6a08d
--
Best Regards
Jammy