# Re: \[PATCH v4\] video: mxsfb: Make sure axi clock is enabled when accessing registers

- From: Tomi Valkeinen \<hidden\>
- Date: 2015-05-07 11:00:39 
- List: linux-fbdev
- Page: https://ratatoskr.run/linux-fbdev/2015/05/4488271
- Thread: https://ratatoskr.run/linux-fbdev/2015/04/4465312/t.md

```text
On 03/04/15 07:51, Liu Ying wrote:
> The LCDIF engines embedded in i.MX6sl and i.MX6sx SoCs need the axi clock
> as the engine's system clock.  The clock should be enabled when accessing
> LCDIF registers, otherwise the kernel would hang up.  We should also keep
> the clock enabled when the engine is being active to scan out frames from
> memory.  This patch makes sure the axi clock is enabled when accessing
> registers so that the kernel hang up issue can be fixed.
> 
> Reported-by: Peter Chen <redacted>
> Tested-by: Peter Chen <redacted>
> Cc: <redacted> # 3.19+
> Signed-off-by: Liu Ying <redacted>
> ---
> v3->v4:
> * To address Tomi's comment, enable/disable the axi clock in
>   mxsfb_pan_display() directly instead of checking the host->enabled flag.
> 
> v2->v3:
> * To address Tomi's comment, improve the commit message only.
> 
> v1->v2:
> * Add 'Tested-by: Peter Chen [ref]' tag.
> * Add 'Cc: [ref] # 3.19+' tag.
> 
>  drivers/video/fbdev/mxsfb.c | 68 +++++++++++++++++++++++++++++++++++----------
>  1 file changed, 54 insertions(+), 14 deletions(-)

Thanks, queued for 4.2.

 Tomi


```

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