[U-Boot] [PATCH] video: ipuv3_fb: skip IPU shutdown if IPU was not enabled before

[Anatolij Gustschin <agust@denx.de>]

Hi Stefano,

On Mon, 28 Aug 2017 18:54:39 +0200
Stefano Babic sbabic at denx.de wrote:
...
> > +	/*
> > +	 * Check if IPU clock was enabled before. Won't access
> > +	 * IPU registers if clock is not enabled.
> > +	 */
> > +	reg = readl(&mxc_ccm->CCGR3);
> > +	if ((reg & MXC_CCM_CCGR3_IPU1_IPU_MASK) == 0)
> > +		return;
> >    
> 
> It looks to me quite weak to simply check if clock is gated. On some
> board clock is gated even if IPU is not active. Do you have a way
> reading inside IPU itself ? Then we can better decide if it was really
> acrive. For example, checking if ipu_enable_channel() was called (and
> DMA registers are set).

we cannot access IPU registers when IPU clock is disabled (register
access will hang the CPU).

Thanks,
Anatolij