Re: [PATCH] drm/rockchip: vop: power off until vop standby take effect

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On 2015年02月02日 15:53, Daniel Vetter wrote:
On Mon, Feb 02, 2015 at 10:30:09AM +0800, Mark yao wrote:
On 2015年02月02日 10:07, Daniel Kurtz wrote:
Hi Mark, Heiko,

On Sat, Jan 31, 2015 at 4:41 PM, Mark Yao <mark.yao@xxxxxxxxxxxxxx> wrote:
Vop standby will take effect end of current frame,
if dsp_hold_valid_irq happen, it means vop standby complete.

we must wait standby complete when we want to disable aclk,
if not, memory bus maybe dead.

Signed-off-by: Mark Yao <mark.yao@xxxxxxxxxxxxxx>
---
  drivers/gpu/drm/rockchip/rockchip_drm_vop.c |   76 ++++++++++++++++++++++-----
  1 file changed, 63 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
index fb25836..47ea61f 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
@@ -89,6 +89,7 @@ struct vop {
         /* mutex vsync_ work */
         struct mutex vsync_mutex;
         bool vsync_work_pending;
+       struct completion dsp_hold_completion;

         const struct vop_data *data;

@@ -382,6 +383,34 @@ static bool is_alpha_support(uint32_t format)
         }
  }

+static void vop_dsp_hold_valid_irq_enable(struct vop *vop)
+{
+       unsigned long flags;
+
+       BUG_ON(!vop->is_enabled);
Re: Heiko "use a WARN_ON":

If the VOP clock is off, then the system will just hang when trying to
write the VOP register so in this case, BUG_ON gives a more reliable
crash dump than the hang.
   In this way, you are right, if vop clocks is disabled, write vop register
will hang system, and the WARN_ON
if (WARN_ON(cond))
	return;

is what we commonly use in i915. Because it's really not any good to use
BUG_ON in drm drivers, at least if you expect anyone to use fbcon on top
of it (i.e. anything even remotely resembling a normal distro): Then the
intial modeset is all done under console_lock, which means that _none_ of
your BUG_ON will ever get out over serial console.

The problem is fbcon locking, but no fool yet signed up to fix it (it's
horrible, I looked ...).
-Daniel
I know this problem, if fbcon locking, and BUG_ON, we can't get any log from serial console, Trouble me many times. So know, if no drm log output, the first thing I do is remove the fbcon lock, and then
we can see the crash dump.

But here, I expect to use BUG_ON, because if BUG happen, vop register will hang system, and WARN_ON
may be have no chance to output.

Mark

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