From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linus Walleij Date: Wed, 17 Feb 2016 16:17:33 +0000 Subject: Re: [PATCH 11/11] ARM: versatile: move CLCD configuration to device tree Message-Id: List-Id: References: <1454594660-7532-1-git-send-email-linus.walleij@linaro.org> <1454594660-7532-12-git-send-email-linus.walleij@linaro.org> <56C438DA.5040109@ti.com> In-Reply-To: <56C438DA.5040109@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-arm-kernel@lists.infradead.org On Wed, Feb 17, 2016 at 10:09 AM, Tomi Valkeinen wrote: >> Tested on Versatile AB with just VGA with the default device tree, >> and with the IB2 daughterboard with the custom IB2 device tree. >> Tested to shunt in XVGA by modifying the device tree and this works >> too. Also tested on QEMU for Versatile in both VGA and Sanyo 2.5" >> mode. I don't have the IB1 daughterboard and its add-on displays, >> but it should work as long as the detection mechanism and device >> tree parameters are sound. > > Well... I don't like this very much. The .dts should contain > descriptions for hardware that is connected. Have you looked at DT > overlays? I think they would be a much better match for this. I'll look into it. I don't know how good those are. They must be overlaid at runtime and anyways exist somewhere in memory so they can be overlaid in there. > What's the SYS_CLCD register? An EEPROM or such, programmed when the > board is manufactured? Is the panel meant to be switchable by the user, > possibly to a panel that's not "standard"? As Russell points out: it's a register that contains a number saying what panel is connected. So it is plug-n-play and I want to preserve this in the patch. The alternative is to make one DTS per display type connected, but that is loosing all the nice plug'n'play :( But if an overlay can do the same, I'm game for it. Yours, Linus Walleij From mboxrd@z Thu Jan 1 00:00:00 1970 From: linus.walleij@linaro.org (Linus Walleij) Date: Wed, 17 Feb 2016 17:17:33 +0100 Subject: [PATCH 11/11] ARM: versatile: move CLCD configuration to device tree In-Reply-To: <56C438DA.5040109@ti.com> References: <1454594660-7532-1-git-send-email-linus.walleij@linaro.org> <1454594660-7532-12-git-send-email-linus.walleij@linaro.org> <56C438DA.5040109@ti.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Feb 17, 2016 at 10:09 AM, Tomi Valkeinen wrote: >> Tested on Versatile AB with just VGA with the default device tree, >> and with the IB2 daughterboard with the custom IB2 device tree. >> Tested to shunt in XVGA by modifying the device tree and this works >> too. Also tested on QEMU for Versatile in both VGA and Sanyo 2.5" >> mode. I don't have the IB1 daughterboard and its add-on displays, >> but it should work as long as the detection mechanism and device >> tree parameters are sound. > > Well... I don't like this very much. The .dts should contain > descriptions for hardware that is connected. Have you looked at DT > overlays? I think they would be a much better match for this. I'll look into it. I don't know how good those are. They must be overlaid at runtime and anyways exist somewhere in memory so they can be overlaid in there. > What's the SYS_CLCD register? An EEPROM or such, programmed when the > board is manufactured? Is the panel meant to be switchable by the user, > possibly to a panel that's not "standard"? As Russell points out: it's a register that contains a number saying what panel is connected. So it is plug-n-play and I want to preserve this in the patch. The alternative is to make one DTS per display type connected, but that is loosing all the nice plug'n'play :( But if an overlay can do the same, I'm game for it. Yours, Linus Walleij