Hi Michael, Thank you for the patch, Could the patch title be a bit better described? Perhaps: media: i2c: adv748x: Correct EAV F-bit handling On 10/05/2019 16:30, Michael Rodin wrote: > According to pages 188 and 193 of the "UG-747: ADV7481 Reference Manual" > [1], the bit 7 (FRAMENUMBER_INTERLACED) of the register csi_tx_top_reg_1f > "sets association of frame number in the FS and FE packets with the F bit > in the EAV/SAV codes". EAV/SAV codes are defined in [2]. > According to [2]: Could you detail where this reference is to help searching for it please? (it looks like Table 2, page 5) > F=0 for field 1 > F=1 for field 2 It would help to indent those lines to make the whole text a bit more readable... > The bit FRAMENUMBER_INTERLACED is not initialized anywhere in the current > version of the adv748x driver and therefore it is always 0, which is the > default value according to [1]. Therefore the current association of field > number from EAV/SAV code with the frame number in CSI FS and FE packets is: > field 1 (top field for PAL, bottom field for NTSC) -> CSI frame number 2 > field 2 (bottom field for PAL, top field for NTSC) -> CSI frame number 1 > But this breaks frame number based field detection of top/bottom fields > in CSI receivers. Therefore it makes sense to initialize the > FRAMENUMBER_INTERLACED bit to 1 so the association is as expected: > field 1 -> frame number 1 > field 2 -> frame number 2 I'm a bit worried by this patch, as it implies that we would have had our fields inverted in our testing, or if they are not - then applying this patch will then invert them! So either way we need to check this carefully. I can see the EAV:F values match the description above in the document... Niklas, how does RCar-CSI determine the top/bottom sequence? Do we have field inversion currently? (or one which is perhaps swapped somewhere along the pipeline in rcar-vin?) > [1] https://www.analog.com/en/products/adv7481.html > [2] https://www.itu.int/rec/R-REC-BT.656-5-200712-I/en > > Suggested-by: Steve Longerbeam <steve_longerbeam@xxxxxxxxxx> > Signed-off-by: Michael Rodin <mrodin@xxxxxxxxxxxxxx> > --- > drivers/media/i2c/adv748x/adv748x-core.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/media/i2c/adv748x/adv748x-core.c b/drivers/media/i2c/adv748x/adv748x-core.c > index f57cd77..4dd1a13 100644 > --- a/drivers/media/i2c/adv748x/adv748x-core.c > +++ b/drivers/media/i2c/adv748x/adv748x-core.c > @@ -278,6 +278,9 @@ static int adv748x_power_up_tx(struct adv748x_csi2 *tx) > usleep_range(1000, 1500); > adv748x_write_check(state, page, 0x31, 0x80, &ret); > > + /* set bit 7 (FRAMENUMBER_INTERLACED) in csi_tx_top_reg_1f */ > + adv748x_write_check(state, page, 0x1f, 0x80, &ret); I think it would be nice to store the bit as macro defines in drivers/media/i2c/adv748x/adv748x.h I appreciate that the rest of this function does not (yet) do that however, (it has been derived from a table of ADI required writes) - but I think now that it is split from a table to a function it could be nice to clean up the 'magic numbers' along the way. Of course if you have time to convert the rest of the function as well (in a separate patch) that might be a nice cleanup, but not required. > + > return ret; > } > > -- Regards -- Kieran
