Re: [PATCH v2 1/3] media: V3s: Add support for Allwinner CSI.

[Maxime Ripard]

On Thu, Jul 27, 2017 at 03:16:44PM +0300, Baruch Siach wrote:
> Hi Yong,
> 
> I managed to get the Frame Done interrupt with the previous version of this 
> driver on the A33 OLinuXino. No data yet (all zeros). I'm still working on it.
> 
> One comment below.
> 
> On Thu, Jul 27, 2017 at 01:01:35PM +0800, Yong Deng wrote:
> > Allwinner V3s SoC have two CSI module. CSI0 is used for MIPI interface
> > and CSI1 is used for parallel interface. This is not documented in
> > datasheet but by testing and guess.
> > 
> > This patch implement a v4l2 framework driver for it.
> > 
> > Currently, the driver only support the parallel interface. MIPI-CSI2,
> > ISP's support are not included in this patch.
> > 
> > Signed-off-by: Yong Deng <yong.deng@xxxxxxxxxxxx>
> > ---
> 
> [...]
> 
> > +static int update_buf_addr(struct sun6i_csi *csi, dma_addr_t addr)
> > +{
> > +	struct sun6i_csi_dev *sdev = sun6i_csi_to_dev(csi);
> > +	/* transform physical address to bus address */
> > +	dma_addr_t bus_addr = addr - 0x40000000;
> 
> What is the source of this magic number? Is it platform dependent? Are there 
> other devices doing DMA that need this adjustment?

This is the RAM base address in most (but not all) Allwinner
SoCs. You'll want to use PHYS_OFFSET instead.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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