Re: [PATCH v15 1/3] drm: rockchip: Add basic drm driver

On 2016年03月14日 21:35, Tomeu Vizoso wrote:

On 2 December 2014 at 10:15, Mark Yao [off-list ref] wrote:

quoted

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
new file mode 100644
index 0000000..e7ca25b
--- /dev/null
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c

@@ -0,0 +1,1455 @@

...

quoted

+static bool vop_crtc_mode_fixup(struct drm_crtc *crtc,
+                               const struct drm_display_mode *mode,
+                               struct drm_display_mode *adjusted_mode)
+{
+       if (adjusted_mode->htotal == 0 || adjusted_mode->vtotal == 0)
+               return false;

Hi Mark,

what's the rationale for this?

Disabling a CRTC as in [0] will cause mode_fixup() to be called with
an empty mode, failing that test.

Removing the check seems to get things working fine for a short while,
but a later modeset invariably gets the VOP to hang (as reported by
[1]).

Do you know why that check was put in place and what exactly could be
causing the hw to hang?

[0] https://cgit.freedesktop.org/xorg/app/intel-gpu-tools/tree/lib/igt_kms.c#n1616
[1] https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/tree/drivers/gpu/drm/rockchip/rockchip_drm_vop.c#n873

Thanks,

Tomeu

Hi Tomeu

Just thinking that "adjusted_mode->htotal == 0 || adjusted_mode->vtotal 
== 0" is not a good mode for vop.

And you said VOP hang, only WARN_ON error message? or system hang, die?

I think maybe crtc disable too fast, vblank is off, then no one can feed the wait_update_complete.
Can you test it again with following patch?
drivers/gpu/drm/rockchip/rockchip_drm_vop.c

@@ -503,6 +503,8 @@ static void vop_crtc_disable(struct drm_crtc *crtc)
         if (!vop->is_enabled)
                 return;
  
+       vop_crtc_wait_for_update(crtc);
+
         drm_crtc_vblank_off(crtc);

Thanks.

-- 
Ｍark Yao


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