linux-kernel - Re: [PATCHv2] omap3isp: add support for CSI1 bus

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Date:   Sat, 04 Mar 2017 20:44:50 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Sakari Ailus <sakari.ailus@....fi>
Cc:     Pavel Machek <pavel@....cz>, mchehab@...nel.org,
        kernel list <linux-kernel@...r.kernel.org>,
        ivo.g.dimitrov.75@...il.com, sre@...nel.org, pali.rohar@...il.com,
        linux-media@...r.kernel.org
Subject: Re: [PATCHv2] omap3isp: add support for CSI1 bus

Hi Sakari,

On Saturday 04 Mar 2017 17:39:46 Sakari Ailus wrote:
> On Sat, Mar 04, 2017 at 03:03:18PM +0200, Sakari Ailus wrote:
> > On Thu, Mar 02, 2017 at 01:38:48PM +0100, Pavel Machek wrote:
> >> 
> >>>> Ok, how about this one?
> >>>> omap3isp: add rest of CSI1 support
> >>>> 
> >>>> CSI1 needs one more bit to be set up. Do just that.
> >>>> 
> >>>> It is not as straightforward as I'd like, see the comments in the
> >>>> code for explanation.
> >>
> >> ...
> >> 
> >>>> +	if (isp->phy_type == ISP_PHY_TYPE_3430) {
> >>>> +		struct media_pad *pad;
> >>>> +		struct v4l2_subdev *sensor;
> >>>> +		const struct isp_ccp2_cfg *buscfg;
> >>>> +
> >>>> +		pad = media_entity_remote_pad(&ccp2
> >>>> ->pads[CCP2_PAD_SINK]);
> >>>> +		sensor = media_entity_to_v4l2_subdev(pad->entity);
> >>>> +		/* Struct isp_bus_cfg has union inside */
> >>>> +		buscfg = &((struct isp_bus_cfg *)sensor->host_priv)
> >>>> ->bus.ccp2;
> >>>> +
> >>>> +		csiphy_routing_cfg_3430(&isp->isp_csiphy2,
> >>>> +					ISP_INTERFACE_CCP2B_PHY1,
> >>> > +					enable, !!buscfg->phy_layer,
> >>> > +					buscfg->strobe_clk_pol);
> >>> 
> >>> You should do this through omap3isp_csiphy_acquire(), and not call
> >>> csiphy_routing_cfg_3430() directly from here.
> >> 
> >> Well, unfortunately omap3isp_csiphy_acquire() does have csi2
> >> assumptions hard-coded :-(.
> >> 
> >> This will probably fail.
> >> 
> >> 	        rval = omap3isp_csi2_reset(phy->csi2);
> >> 	        if (rval < 0)
> >> 		                goto done;
> > 
> > Could you try to two patches I've applied on the ccp2 branch (I'll remove
> > them if there are issues).
> > 
> > That's compile tested for now only.
> 
> One more thing. What's needed for configuring the PHY for CCP2?
> 
> For instance, is the CSI-2 PHY regulator still needed in
> omap3isp_csiphy_acquire()? One way to do this might go to see the original
> driver for N900; I don't have the TRM at hand right now.

The OMAP34xx TRM and data manual both mention separate VDDS power supplies for 
the CSIb and CSI2 I/O complexes.

vdds_csi2		CSI2 Complex I/O
vdds_csib		CSIb Complex I/O

On OMAP36xx, we instead have

vdda_csiphy1		Input power for camera PHY buffer
vdda_csiphy2		Input power for camera PHY buffer

We need to enable the vds_csib regulator to operate the CSI1/CCP2 PHY, but 
that regulator gets enabled in ispccp2.c as that module is powered by the 
vdds_csib supply on OMAP34xx. However, it won't hurt to do so, and the code 
could be simpler if we manage the regulators the same way on OMAP34xx and 
OMAP36xx.

-- 
Regards,

Laurent Pinchart