Dne ponedeljek, 11. april 2022 ob 06:34:15 CEST je Samuel Holland napisal(a):
> commit b4bdc4fbf8d0 ("soc: sunxi: Deal with the MBUS DMA offsets in a
> central place") added a platform device notifier that sets the DMA
> offset for all of the display engine frontend and backend devices.
>
> The code applying the offset to DMA buffer physical addresses was then
> removed from the backend driver in commit 756668ba682e ("drm/sun4i:
> backend: Remove the MBUS quirks"), but the code subtracting PHYS_OFFSET
> was left in the frontend driver.
>
> As a result, the offset was applied twice in the frontend driver. This
> likely went unnoticed because it only affects specific configurations
> (scaling or certain pixel formats) where the frontend is used, on boards
> with both one of these older SoCs and more than 1 GB of DRAM.
>
> In addition, the references to PHYS_OFFSET prevent compiling the driver
> on architectures where PHYS_OFFSET is not defined.
>
> Fixes: b4bdc4fbf8d0 ("soc: sunxi: Deal with the MBUS DMA offsets in a central
place")
> Signed-off-by: Samuel Holland <samuel@xxxxxxxxxxxx>
Good catch! Actually, people complained about non-working display on
Cubietruck IIRC, which has 2 GB of RAM.
Did you test this on HW?
Reviewed-by: Jernej Skrabec <jernej.skrabec@xxxxxxxxx>
Best regards,
Jernej
> ---
>
> drivers/gpu/drm/sun4i/sun4i_frontend.c | 3 ---
> 1 file changed, 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/sun4i/sun4i_frontend.c b/drivers/gpu/drm/sun4i/
sun4i_frontend.c
> index 56ae38389db0..462fae73eae9 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_frontend.c
> +++ b/drivers/gpu/drm/sun4i/sun4i_frontend.c
> @@ -222,13 +222,11 @@ void sun4i_frontend_update_buffer(struct sun4i_frontend
*frontend,
>
> /* Set the physical address of the buffer in memory */
> paddr = drm_fb_cma_get_gem_addr(fb, state, 0);
> - paddr -= PHYS_OFFSET;
> DRM_DEBUG_DRIVER("Setting buffer #0 address to %pad\n", &paddr);
> regmap_write(frontend->regs, SUN4I_FRONTEND_BUF_ADDR0_REG, paddr);
>
> if (fb->format->num_planes > 1) {
> paddr = drm_fb_cma_get_gem_addr(fb, state, swap ? 2 :
1);
> - paddr -= PHYS_OFFSET;
> DRM_DEBUG_DRIVER("Setting buffer #1 address to %pad\n",
&paddr);
> regmap_write(frontend->regs,
SUN4I_FRONTEND_BUF_ADDR1_REG,
> paddr);
> @@ -236,7 +234,6 @@ void sun4i_frontend_update_buffer(struct sun4i_frontend
*frontend,
>
> if (fb->format->num_planes > 2) {
> paddr = drm_fb_cma_get_gem_addr(fb, state, swap ? 1 :
2);
> - paddr -= PHYS_OFFSET;
> DRM_DEBUG_DRIVER("Setting buffer #2 address to %pad\n",
&paddr);
> regmap_write(frontend->regs,
SUN4I_FRONTEND_BUF_ADDR2_REG,
> paddr);
> --
> 2.35.1
>
>
