Messages in this thread | | | Subject | Re: [PATCH v4 23/36] media: imx: Add MIPI CSI-2 Receiver subdev driver | From | Steve Longerbeam <> | Date | Wed, 22 Feb 2017 16:09:23 -0800 |
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On 02/22/2017 04:06 PM, Steve Longerbeam wrote: > > > On 02/17/2017 03:06 AM, Russell King - ARM Linux wrote: >> On Fri, Feb 17, 2017 at 11:47:59AM +0100, Philipp Zabel wrote: >>> On Wed, 2017-02-15 at 18:19 -0800, Steve Longerbeam wrote: >>>> +static void csi2_dphy_init(struct csi2_dev *csi2) >>>> +{ >>>> + /* >>>> + * FIXME: 0x14 is derived from a fixed D-PHY reference >>>> + * clock from the HSI_TX PLL, and a fixed target lane max >>>> + * bandwidth of 300 Mbps. This value should be derived >>> >>> If the table in https://community.nxp.com/docs/DOC-94312 is correct, >>> this should be 850 Mbps. Where does this 300 Mbps value come from? >> >> I thought you had some code to compute the correct value, although >> I guess we've lost the ability to know how fast the sensor is going >> to drive the link. >> >> Note that the IMX219 currently drives the data lanes at 912Mbps almost >> exclusively, as I've yet to finish working out how to derive the PLL >> parameters. (I have something that works, but it currently takes on >> the order of 100k iterations to derive the parameters. gcd() doesn't >> help you in this instance.) > > Hi Russell, > > As I mentioned, I've added code to imx6-mipi-csi2 to determine the > sources link frequency via V4L2_CID_LINK_FREQ. If you were to implement > this control and return 912 Mbps-per-lane,
argh, I mean return 912 / 2.
Steve
the D-PHY will be programmed > correctly for the IMX219 (at least, that is the theory anyway). > > Alternatively, I could up the default in imx6-mipi-csi2 to 950 > Mbps. I will have to test that to make sure it still works with > OV5640 and tc358743. > > Steve
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