From mboxrd@z Thu Jan  1 00:00:00 1970
From: Anatolij Gustschin <agust@denx.de>
Date: Mon, 28 Aug 2017 20:23:12 +0200
Subject: [U-Boot] [PATCH] video: ipuv3_fb: skip IPU shutdown if IPU was
 not enabled before
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 <1d1ff220-f225-7d32-061f-6b9c738a52bf@denx.de>
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To: u-boot@lists.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