Re: [PATCH 0/4] OMAPDSS: DT support for N900 panel

On 2013-12-19 02:51, Sebastian Reichel wrote:

On Wed, Dec 18, 2013 at 10:55:37PM +0100, Sebastian Reichel wrote:

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On Tue, Dec 17, 2013 at 07:29:34PM +0200, Tomi Valkeinen wrote:

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I added N900 display DT support on top of my v2 series, including
pinmuxing. Can you check if it looks right and works?

git://git.kernel.org/pub/scm/linux/kernel/git/tomba/linux.git work/dss-dt

I just tried it and it does not work. On a first look the pinmuxing
looks fishy: 0x0d4 is muxed two times.

Hmm, so it is.

I'm not really familiar with SDI, I just muxed all the SDI pins, except
datapair3. I previously thought that there's only the data and clock
pairs for SDI, but the TRM revealed more sdi pins, so I included them.
It is well possible that these can be removed:

0x0d0 (PIN_OUTPUT | MUX_MODE1)   /* dss_data18.sdi_vsync */
0x0d2 (PIN_OUTPUT | MUX_MODE1)   /* dss_data19.sdi_hsync */
0x0d4 (PIN_OUTPUT | MUX_MODE1)   /* dss_data20.sdi_den */
0x0d6 (PIN_OUTPUT | MUX_MODE1)   /* dss_data21.sdi_stp */

Just removing the dss_data20.sdi_den pin was enough to get a working display. I
don't know if the other pins are needed, because the display pins are already
muxed correctly by the bootloader.

I just had a look in the leaked n900 schematics. According to it the
following pins are connected to the display:

DSS_DATA20 (E28)     GPIO 90         LCD_RST
DSS_DATA10 (AD28)    SDI_DAT1N       CDP 0
DSS_DATA11 (AD27)    SDI_DAT1P       CDP 1
DSS_DATA12 (AB28)    SDI_DAT2N       CDP 2
DSS_DATA13 (AB27)    SDI_DAT2P       CDP 3
DSS_DATA14 (AA28)    SDI_DAT3N       CDP 4
DSS_DATA15 (AA27)    SDI_DAT3P       CDP 5
DSS_DATA22 (AC27)    SDI_CLKP        CDP 6
DSS_DATA23 (AC28)    SDI_CLKN        CDP 7

I also noticed that dss_data19.sdi_hsync is used as gpio 89 for the
N900's proximity sensor. Thus I suggest the following SDI pin muxing:

	dss_sdi_pins: pinmux_dss_sdi_pins {
		pinctrl-single,pins = <
			0x0c0 (PIN_OUTPUT | MUX_MODE1)   /* dss_data10.sdi_dat1n */
			0x0c2 (PIN_OUTPUT | MUX_MODE1)   /* dss_data11.sdi_dat1p */
			0x0c4 (PIN_OUTPUT | MUX_MODE1)   /* dss_data12.sdi_dat2n */
			0x0c6 (PIN_OUTPUT | MUX_MODE1)   /* dss_data13.sdi_dat2p */
			0x0c8 (PIN_OUTPUT | MUX_MODE1)   /* dss_data14.sdi_dat3n */
			0x0ca (PIN_OUTPUT | MUX_MODE1)   /* dss_data15.sdi_dat3p */

			0x0d8 (PIN_OUTPUT | MUX_MODE1)   /* dss_data22.sdi_clkp */
			0x0da (PIN_OUTPUT | MUX_MODE1)   /* dss_data23.sdi_clkn */
		>;
	};

Thanks, I'll do the modifications. The dat3 lines are not needed, but if
they're connected to the panel, I don't see any harm in muxing them.

Although, makes me wonder. If the panel supports only 2 datalanes, why
does it have connectors for 3? And if it supports 3, why would N900 use
only 2?

Are you able to check if the bootloader muxes dat3 to SDI mode?

 Tomi