[PATCH] media: platform: Fix a kernel warning on clk control
Jae Hyun Yoo
jae.hyun.yoo at linux.intel.com
Sat Mar 30 07:47:04 AEDT 2019
On 3/29/2019 1:08 PM, Eddie James wrote:
> On 3/28/19 4:25 PM, Jae Hyun Yoo wrote:
>> To prevent this issue, this commit adds spinlock protection and clock
>> status checking logic into the Aspeed video engine driver.
> Thanks Jae. Do you have a reliable way to reproduce this? Haven't seen
> it myself.
It could be observed when user space releases a video engine dev entry
handle while video mode is changing. You could reproduce it by repeating
reload of KVM web page just after trigger a host reset. It rarely
>> + bool is_video_on;
> This can probably be a flag, like VIDEO_CLOCKS_ON, not a new boolean.
Okay, I'll add the bit field into video->flags.
>> + aspeed_video_reset(video);
> I'm working on a patch to remove the use of the reset line too.
Right, since clk-aspeed module can trigger a reset while enabling the
vclk or eclk, it could be removed later, but this patch is not for that.
>> + spin_lock(&video->lock);
> Is there a reason you're locking extra code? Why not put the lock in the
> aspeed_video_on/off functions?
aspeed_video_on() and aspeed_video_off() can be called from driver
context and from interrupt context so some video enable/disable
relating code also need to be serialized.
Will submit v2 soon after replacing the boolean variable with
More information about the Linux-aspeed