From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753073AbeDSJdf (ORCPT ); Thu, 19 Apr 2018 05:33:35 -0400 Received: from mirror2.csie.ntu.edu.tw ([140.112.30.76]:35656 "EHLO wens.csie.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752783AbeDSJce (ORCPT ); Thu, 19 Apr 2018 05:32:34 -0400 From: Chen-Yu Tsai To: Maxime Ripard , David Airlie , Thierry Reding , Rob Herring , Mark Rutland Cc: Chen-Yu Tsai , dri-devel@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, Jonathan Liu Subject: [PATCH 0/6] drm/sun4i: Support color dithering for LCD panels Date: Thu, 19 Apr 2018 17:32:19 +0800 Message-Id: <20180419093225.614-1-wens@csie.org> X-Mailer: git-send-email 2.17.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dithering is a method of approximating a color from a mixture of other colors when the required color isn't available. It reduces color banding artifacts that can be observed when displaying gradients (e.g. grayscale gradients). This may occur when the image that needs to be displayed is 24-bit but the LCD panel is a lower bit depth and does not perform dithering on its own. The TCON (LCD controller) found in Allwinner SoCs has hardware support for dithering on channel 0, the channel used to feed LCD panels. This series adds support for it. Patch 1 reworks the mode set function for the CPU interface to pass the encoder object, so it can be passed to other helper functions. Patch 2 renames the dithering related register macros to reflect the fact that dithering is only supported on channel 0. Patch 3 adds support for dithering on all LCD panel output types. Patch 4 adds support for Banana Pi's 7" DPI LCD panel. Patch 5 adds a pinmux setting for RGB888 for the Allwinner A20 SoC. This change has been sent by others before. Patch 6 provides an example for enabling the Banana Pi 7" DPI LCD panel on the Banana Pi M1+. This should not be merged. I will likely rework this into an overlay in the future. Note that I was only able to test dithering with DPI, as I do not have other panel types. However the underlying concept and core code is the same, as are the drm objects accessed. Nevertheless I'm hoping Jonathan can test LVDS and Maxime can test MIPI DSI. Also it seems pwm-backlight hardware is unusable at the moment. I'm not sure whether the pwm-backlight or sun4i-pwm driver is to blame. I had to manually poke the pwm registers so the LCD backlight wouldn't be completely black. Regards ChenYu Chen-Yu Tsai (5): drm/sun4i: tcon: Pass drm_encoder * into sun4i_tcon0_mode_set_cpu drm/sun4i: tcon: Rename Dithering related register macros drm/panel: simple: Add support for Banana Pi 7" S070WV20-CT16 panel ARM: dts: sun7i: add pinmux setting for RGB888 output for LCD0 [DO NOT MERGE] ARM: dts: sun7i: bananapi-m1-plus: Enable Bananapi 7" 800x480 RGB LCD panel Jonathan Liu (1): drm/sun4i: tcon: Add dithering support for RGB565/RGB666 LCD panels .../display/panel/bananapi,s070wv20-ct16.txt | 7 ++ .../boot/dts/sun7i-a20-bananapi-m1-plus.dts | 61 +++++++++++++++ arch/arm/boot/dts/sun7i-a20.dtsi | 11 +++ drivers/gpu/drm/panel/panel-simple.c | 25 ++++++ drivers/gpu/drm/sun4i/sun4i_tcon.c | 76 ++++++++++++++++--- drivers/gpu/drm/sun4i/sun4i_tcon.h | 27 ++++--- 6 files changed, 186 insertions(+), 21 deletions(-) create mode 100644 Documentation/devicetree/bindings/display/panel/bananapi,s070wv20-ct16.txt -- 2.17.0 From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chen-Yu Tsai Subject: [PATCH 0/6] drm/sun4i: Support color dithering for LCD panels Date: Thu, 19 Apr 2018 17:32:19 +0800 Message-ID: <20180419093225.614-1-wens@csie.org> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Maxime Ripard , David Airlie , Thierry Reding , Rob Herring , Mark Rutland Cc: devicetree@vger.kernel.org, Jonathan Liu , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Chen-Yu Tsai , linux-arm-kernel@lists.infradead.org List-Id: devicetree@vger.kernel.org RGl0aGVyaW5nIGlzIGEgbWV0aG9kIG9mIGFwcHJveGltYXRpbmcgYSBjb2xvciBmcm9tIGEgbWl4 dHVyZSBvZiBvdGhlcgpjb2xvcnMgd2hlbiB0aGUgcmVxdWlyZWQgY29sb3IgaXNuJ3QgYXZhaWxh YmxlLiBJdCByZWR1Y2VzIGNvbG9yCmJhbmRpbmcgYXJ0aWZhY3RzIHRoYXQgY2FuIGJlIG9ic2Vy dmVkIHdoZW4gZGlzcGxheWluZyBncmFkaWVudHMKKGUuZy4gZ3JheXNjYWxlIGdyYWRpZW50cyku IFRoaXMgbWF5IG9jY3VyIHdoZW4gdGhlIGltYWdlIHRoYXQgbmVlZHMKdG8gYmUgZGlzcGxheWVk IGlzIDI0LWJpdCBidXQgdGhlIExDRCBwYW5lbCBpcyBhIGxvd2VyIGJpdCBkZXB0aCBhbmQKZG9l cyBub3QgcGVyZm9ybSBkaXRoZXJpbmcgb24gaXRzIG93bi4KClRoZSBUQ09OIChMQ0QgY29udHJv bGxlcikgZm91bmQgaW4gQWxsd2lubmVyIFNvQ3MgaGFzIGhhcmR3YXJlIHN1cHBvcnQKZm9yIGRp dGhlcmluZyBvbiBjaGFubmVsIDAsIHRoZSBjaGFubmVsIHVzZWQgdG8gZmVlZCBMQ0QgcGFuZWxz LiBUaGlzCnNlcmllcyBhZGRzIHN1cHBvcnQgZm9yIGl0LgoKUGF0Y2ggMSByZXdvcmtzIHRoZSBt b2RlIHNldCBmdW5jdGlvbiBmb3IgdGhlIENQVSBpbnRlcmZhY2UgdG8gcGFzcwp0aGUgZW5jb2Rl ciBvYmplY3QsIHNvIGl0IGNhbiBiZSBwYXNzZWQgdG8gb3RoZXIgaGVscGVyIGZ1bmN0aW9ucy4K ClBhdGNoIDIgcmVuYW1lcyB0aGUgZGl0aGVyaW5nIHJlbGF0ZWQgcmVnaXN0ZXIgbWFjcm9zIHRv IHJlZmxlY3QgdGhlCmZhY3QgdGhhdCBkaXRoZXJpbmcgaXMgb25seSBzdXBwb3J0ZWQgb24gY2hh bm5lbCAwLgoKUGF0Y2ggMyBhZGRzIHN1cHBvcnQgZm9yIGRpdGhlcmluZyBvbiBhbGwgTENEIHBh bmVsIG91dHB1dCB0eXBlcy4KClBhdGNoIDQgYWRkcyBzdXBwb3J0IGZvciBCYW5hbmEgUGkncyA3 IiBEUEkgTENEIHBhbmVsLgoKUGF0Y2ggNSBhZGRzIGEgcGlubXV4IHNldHRpbmcgZm9yIFJHQjg4 OCBmb3IgdGhlIEFsbHdpbm5lciBBMjAgU29DLgpUaGlzIGNoYW5nZSBoYXMgYmVlbiBzZW50IGJ5 IG90aGVycyBiZWZvcmUuCgpQYXRjaCA2IHByb3ZpZGVzIGFuIGV4YW1wbGUgZm9yIGVuYWJsaW5n IHRoZSBCYW5hbmEgUGkgNyIgRFBJIExDRCBwYW5lbApvbiB0aGUgQmFuYW5hIFBpIE0xKy4gVGhp cyBzaG91bGQgbm90IGJlIG1lcmdlZC4gSSB3aWxsIGxpa2VseSByZXdvcmsKdGhpcyBpbnRvIGFu IG92ZXJsYXkgaW4gdGhlIGZ1dHVyZS4KCk5vdGUgdGhhdCBJIHdhcyBvbmx5IGFibGUgdG8gdGVz dCBkaXRoZXJpbmcgd2l0aCBEUEksIGFzIEkgZG8gbm90IGhhdmUKb3RoZXIgcGFuZWwgdHlwZXMu IEhvd2V2ZXIgdGhlIHVuZGVybHlpbmcgY29uY2VwdCBhbmQgY29yZSBjb2RlIGlzIHRoZQpzYW1l LCBhcyBhcmUgdGhlIGRybSBvYmplY3RzIGFjY2Vzc2VkLiBOZXZlcnRoZWxlc3MgSSdtIGhvcGlu ZyBKb25hdGhhbgpjYW4gdGVzdCBMVkRTIGFuZCBNYXhpbWUgY2FuIHRlc3QgTUlQSSBEU0kuCgpB bHNvIGl0IHNlZW1zIHB3bS1iYWNrbGlnaHQgaGFyZHdhcmUgaXMgdW51c2FibGUgYXQgdGhlIG1v bWVudC4gSSdtIG5vdApzdXJlIHdoZXRoZXIgdGhlIHB3bS1iYWNrbGlnaHQgb3Igc3VuNGktcHdt IGRyaXZlciBpcyB0byBibGFtZS4gSSBoYWQgdG8KbWFudWFsbHkgcG9rZSB0aGUgcHdtIHJlZ2lz dGVycyBzbyB0aGUgTENEIGJhY2tsaWdodCB3b3VsZG4ndCBiZQpjb21wbGV0ZWx5IGJsYWNrLgoK ClJlZ2FyZHMKQ2hlbll1CgpDaGVuLVl1IFRzYWkgKDUpOgogIGRybS9zdW40aTogdGNvbjogUGFz cyBkcm1fZW5jb2RlciAqIGludG8gc3VuNGlfdGNvbjBfbW9kZV9zZXRfY3B1CiAgZHJtL3N1bjRp OiB0Y29uOiBSZW5hbWUgRGl0aGVyaW5nIHJlbGF0ZWQgcmVnaXN0ZXIgbWFjcm9zCiAgZHJtL3Bh bmVsOiBzaW1wbGU6IEFkZCBzdXBwb3J0IGZvciBCYW5hbmEgUGkgNyIgUzA3MFdWMjAtQ1QxNiBw YW5lbAogIEFSTTogZHRzOiBzdW43aTogYWRkIHBpbm11eCBzZXR0aW5nIGZvciBSR0I4ODggb3V0 cHV0IGZvciBMQ0QwCiAgW0RPIE5PVCBNRVJHRV0gQVJNOiBkdHM6IHN1bjdpOiBiYW5hbmFwaS1t MS1wbHVzOiBFbmFibGUgQmFuYW5hcGkgNyIKICAgIDgwMHg0ODAgUkdCIExDRCBwYW5lbAoKSm9u YXRoYW4gTGl1ICgxKToKICBkcm0vc3VuNGk6IHRjb246IEFkZCBkaXRoZXJpbmcgc3VwcG9ydCBm b3IgUkdCNTY1L1JHQjY2NiBMQ0QgcGFuZWxzCgogLi4uL2Rpc3BsYXkvcGFuZWwvYmFuYW5hcGks czA3MHd2MjAtY3QxNi50eHQgIHwgIDcgKysKIC4uLi9ib290L2R0cy9zdW43aS1hMjAtYmFuYW5h cGktbTEtcGx1cy5kdHMgICB8IDYxICsrKysrKysrKysrKysrKwogYXJjaC9hcm0vYm9vdC9kdHMv c3VuN2ktYTIwLmR0c2kgICAgICAgICAgICAgIHwgMTEgKysrCiBkcml2ZXJzL2dwdS9kcm0vcGFu ZWwvcGFuZWwtc2ltcGxlLmMgICAgICAgICAgfCAyNSArKysrKysKIGRyaXZlcnMvZ3B1L2RybS9z dW40aS9zdW40aV90Y29uLmMgICAgICAgICAgICB8IDc2ICsrKysrKysrKysrKysrKystLS0KIGRy aXZlcnMvZ3B1L2RybS9zdW40aS9zdW40aV90Y29uLmggICAgICAgICAgICB8IDI3ICsrKystLS0K IDYgZmlsZXMgY2hhbmdlZCwgMTg2IGluc2VydGlvbnMoKyksIDIxIGRlbGV0aW9ucygtKQogY3Jl YXRlIG1vZGUgMTAwNjQ0IERvY3VtZW50YXRpb24vZGV2aWNldHJlZS9iaW5kaW5ncy9kaXNwbGF5 L3BhbmVsL2JhbmFuYXBpLHMwNzB3djIwLWN0MTYudHh0CgotLSAKMi4xNy4wCgpfX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fXwpkcmktZGV2ZWwgbWFpbGluZyBs aXN0CmRyaS1kZXZlbEBsaXN0cy5mcmVlZGVza3RvcC5vcmcKaHR0cHM6Ly9saXN0cy5mcmVlZGVz a3RvcC5vcmcvbWFpbG1hbi9saXN0aW5mby9kcmktZGV2ZWwK From mboxrd@z Thu Jan 1 00:00:00 1970 From: wens@csie.org (Chen-Yu Tsai) Date: Thu, 19 Apr 2018 17:32:19 +0800 Subject: [PATCH 0/6] drm/sun4i: Support color dithering for LCD panels Message-ID: <20180419093225.614-1-wens@csie.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Dithering is a method of approximating a color from a mixture of other colors when the required color isn't available. It reduces color banding artifacts that can be observed when displaying gradients (e.g. grayscale gradients). This may occur when the image that needs to be displayed is 24-bit but the LCD panel is a lower bit depth and does not perform dithering on its own. The TCON (LCD controller) found in Allwinner SoCs has hardware support for dithering on channel 0, the channel used to feed LCD panels. This series adds support for it. Patch 1 reworks the mode set function for the CPU interface to pass the encoder object, so it can be passed to other helper functions. Patch 2 renames the dithering related register macros to reflect the fact that dithering is only supported on channel 0. Patch 3 adds support for dithering on all LCD panel output types. Patch 4 adds support for Banana Pi's 7" DPI LCD panel. Patch 5 adds a pinmux setting for RGB888 for the Allwinner A20 SoC. This change has been sent by others before. Patch 6 provides an example for enabling the Banana Pi 7" DPI LCD panel on the Banana Pi M1+. This should not be merged. I will likely rework this into an overlay in the future. Note that I was only able to test dithering with DPI, as I do not have other panel types. However the underlying concept and core code is the same, as are the drm objects accessed. Nevertheless I'm hoping Jonathan can test LVDS and Maxime can test MIPI DSI. Also it seems pwm-backlight hardware is unusable at the moment. I'm not sure whether the pwm-backlight or sun4i-pwm driver is to blame. I had to manually poke the pwm registers so the LCD backlight wouldn't be completely black. Regards ChenYu Chen-Yu Tsai (5): drm/sun4i: tcon: Pass drm_encoder * into sun4i_tcon0_mode_set_cpu drm/sun4i: tcon: Rename Dithering related register macros drm/panel: simple: Add support for Banana Pi 7" S070WV20-CT16 panel ARM: dts: sun7i: add pinmux setting for RGB888 output for LCD0 [DO NOT MERGE] ARM: dts: sun7i: bananapi-m1-plus: Enable Bananapi 7" 800x480 RGB LCD panel Jonathan Liu (1): drm/sun4i: tcon: Add dithering support for RGB565/RGB666 LCD panels .../display/panel/bananapi,s070wv20-ct16.txt | 7 ++ .../boot/dts/sun7i-a20-bananapi-m1-plus.dts | 61 +++++++++++++++ arch/arm/boot/dts/sun7i-a20.dtsi | 11 +++ drivers/gpu/drm/panel/panel-simple.c | 25 ++++++ drivers/gpu/drm/sun4i/sun4i_tcon.c | 76 ++++++++++++++++--- drivers/gpu/drm/sun4i/sun4i_tcon.h | 27 ++++--- 6 files changed, 186 insertions(+), 21 deletions(-) create mode 100644 Documentation/devicetree/bindings/display/panel/bananapi,s070wv20-ct16.txt -- 2.17.0