On Sat, Sep 2, 2017 at 11:17 PM, Linus Walleij <linus.walleij@xxxxxxxxxx> wrote: > On Thu, Aug 17, 2017 at 10:44 PM, Rob Herring <robh@xxxxxxxxxx> wrote: >> On Sun, Aug 13, 2017 at 01:44:47PM +0200, Linus Walleij wrote: > >>> This adds device tree bindings for the Ilitek ILI9322 >>> 320x240 TFT panel driver. >>> >>> Cc: devicetree@xxxxxxxxxxxxxxx >>> Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx> > (...) >>> +Optional properties: >>> + - width-mm: physical panel width [mm] >>> + - height-mm: physical panel height [mm] >>> + - vcc-supply: core voltage supply, see regulator/regulator.txt >>> + - iovcc-supply: voltage supply for the interface input/output signals, >>> + see regulator/regulator.txt >>> + - vci-supply: voltage supply for analog parts, see regulator/regulator.txt >>> + - reset-gpios: a GPIO spec for the reset pin, see gpio/gpio.txt >>> + - ilitek,vreg1out-microvolt: the output in microvolts for the VREGOUT1 >>> + regulator used to drive the physical display. Valid ranges are 3600 thru >>> + 6000 in 100 microvolt increments. If not specified, hardware defaults will >>> + be used (4.5V). >>> + - ilitek,vcom-amplitude-percent: the percentage of VREGOUT1 used for the >>> + peak-to-peak amplitude of the communcation signals to the physical display. >>> + Valid ranges are 70 thru 132 percent in increments if two percent. Odd >>> + percentages will be truncated. If not specified, hardware defaults will be >>> + used (114%). >>> + - ilitek,vcom-high-percent: the percentage of VREGOUT1 used for the peak >>> + voltage on the communications link. Valid ranges are 37 thru 100 percent. >>> + If not specified, hardware defaults will be used (91%). >>> + - ilitek,gamma-correction-neg: a set of 8 nybbles describing negative >>> + gamma correction for voltages V1 thru V8. Valid range 0..15 >>> + - ilitek,gamma-correction-pos: a set of 8 nybbles describing positive >>> + gamma correction for voltages V1 thru V8. Valid range 0..15 >>> + These adjust what grayscale voltage will be output for input data V1 = 0, >>> + V2 = 16, V3 = 48, V4 = 96, V5 = 160, V6 = 208, V7 = 240 and V8 = 255. >>> + The curve is shaped like this: >>> + >>> + ^ >>> + | V8 >>> + | V7 >>> + | V6 >>> + | V5 >>> + | V4 >>> + | V3 >>> + | V2 >>> + | V1 >>> + +-----------------------------------------------------------> >>> + 0 16 48 96 160 208 240 255 >>> + >>> + The negative and postive gamma values adjust the V1 thru V8 up/down >>> + according to the datasheet specifications. This is a property of the >>> + physical display connected to the display controller and may vary. >>> + If defined, both arrays must be supplied in full. If the properties >>> + are not supplied, hardware defaults will be used. >> >> Normally, we the physical panel is described which would imply all these >> settings. Are there lots of panels with this controller that would >> justify all these settings? > > The datasheet for the ili9322 just says it "drives panels" essentially. > Googling around gives at hand that it is used pretty frequently in > Shenzhen China for adapting different off-the-shelf panels to > different inputs. > > I can't really answer how many of these products that run one or > another OS using device tree to describe the configuration. It feels more > like I'm paving the road for others to travel. > > Probably other Ilitek panel adapters will need something similar. > >>> + - ilitek,entry-mode: the panel can be connected to various input streams >>> + and four of them can be selected by electronic straps on the display. >>> + However it is possible to select another mode or override the >>> + electronic default with this property. Valid values: >>> + 0: 8 bit serial RGB through >>> + 1: 8 bit serial RGB aligned >>> + 2: 8 bit serial RGB dummy 320x240 >>> + 3: 8 bit serial RGB dummy 360x240 >>> + 4: disabled >>> + 5: 24 bit parallel RGB through >>> + 6: 24 bit parallel RGB aligned >>> + 7: 24 bit YUV 640Y 320CbCr >>> + 8: 24 bit YUV 720Y 360CbCr >>> + 9: disabled >>> + 10: 8 bit ITU-R BT.656 720Y 360CbCr >>> + 11: 8 bit ITU-R BT.656 640Y 320CbCr >> >> To some extent, we have some standard bindings to describe this. > > I don't find any. Maybe I'm looking in the wrong places :( > > These are closest associated with the DRM "media bus formats" > in Linux include/uapi/linux/media-bus-format.h > such as: > > #define MEDIA_BUS_FMT_RGB444_1X12 0x1016 > #define MEDIA_BUS_FMT_RGB444_2X8_PADHI_BE 0x1001 > #define MEDIA_BUS_FMT_RGB444_2X8_PADHI_LE 0x1002 > #define MEDIA_BUS_FMT_RGB555_2X8_PADHI_BE 0x1003 > #define MEDIA_BUS_FMT_RGB555_2X8_PADHI_LE 0x1004 > #define MEDIA_BUS_FMT_RGB565_1X16 0x1017 > #define MEDIA_BUS_FMT_BGR565_2X8_BE 0x1005 > #define MEDIA_BUS_FMT_BGR565_2X8_LE 0x1006 > #define MEDIA_BUS_FMT_RGB565_2X8_BE 0x1007 > #define MEDIA_BUS_FMT_RGB565_2X8_LE 0x1008 > #define MEDIA_BUS_FMT_RGB666_1X18 0x1009 > #define MEDIA_BUS_FMT_RBG888_1X24 0x100e > #define MEDIA_BUS_FMT_RGB666_1X24_CPADHI 0x1015 > #define MEDIA_BUS_FMT_RGB666_1X7X3_SPWG 0x1010 > (...) > > We can surely regard this bus format list as standard and > copy and extend it in DT (it does not have ITU-R formats for > the moment) but I don't know if that is wise. > > Also the input modes of ili9322 is coupled with resolution so > it would need two more cells or so for resolution so I feel > it would over-complicate things for these 12 enumerators. Can we proceed with these patches? Any opinion from DT or panel maintainers? Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
