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

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On 2015年02月04日 11:48, Daniel Kurtz wrote:
On Feb 4, 2015 11:38 AM, "Mark yao" <mark.yao@xxxxxxxxxxxxxx> wrote:
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.
Yeah, but danvet is suggesting we just return immediately on the
WARN_ON condition, to avoid accessing the vop registers and hanging.

Thus, the WARN_ON will have a chance to put out (unless the early
return path goes off and finds some other unprotected path goes to
access unlocked registers).

-Dan
All right, I got it.
Mark





--
Mark Yao 姚智情

Rockchip 福州瑞芯微电子有限公司

Fuzhou Headquarters

Addr:No.21 Building, A District, Fuzhou

Software Park, 89 Soft Avenue, Tongpan Road,

Gulou District, Fuzhou (350003)

地址:福建省福州市铜盘路软件大道89号软件园A区21号楼 (350003)

Tel:(86-0591)83991906 - 8296

E-mail:mark.yao@xxxxxxxxxxxxxx


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