From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932973AbcLIA5j (ORCPT ); Thu, 8 Dec 2016 19:57:39 -0500 Received: from mail-out.m-online.net ([212.18.0.9]:41529 "EHLO mail-out.m-online.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752356AbcLIA5i (ORCPT ); Thu, 8 Dec 2016 19:57:38 -0500 X-Auth-Info: f9v2Hf5iMZpqiN9QduCJRZzQGMAdieTTfcDuTfv44Ek= Subject: Re: [PATCH] drm/mxsfb: use bus_format to determine LCD bus width To: Stefan Agner References: <20161208225243.19792-1-stefan@agner.ch> Cc: airlied@linux.ie, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org From: Marek Vasut Message-ID: <878d504a-5689-1dd9-2e5e-fad085b7406e@denx.de> Date: Fri, 9 Dec 2016 00:33:34 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Icedove/45.4.0 MIME-Version: 1.0 In-Reply-To: <20161208225243.19792-1-stefan@agner.ch> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/08/2016 11:52 PM, Stefan Agner wrote: > The LCD bus width does not need to align with the pixel format. The > LCDIF controller automatically converts between pixel formats and > bus width by padding or dropping LSBs. > > The DRM subsystem has the notion of bus_format which allows to > determine what bus_formats are supported by the display. Choose the > first available or fallback to 24 bit if none are available. > > Signed-off-by: Stefan Agner > --- > drivers/gpu/drm/mxsfb/mxsfb_crtc.c | 28 +++++++++++++++++++++++++--- > drivers/gpu/drm/mxsfb/mxsfb_regs.h | 1 + > 2 files changed, 26 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/mxsfb/mxsfb_crtc.c b/drivers/gpu/drm/mxsfb/mxsfb_crtc.c > index 4bcc8a3..00fa244 100644 > --- a/drivers/gpu/drm/mxsfb/mxsfb_crtc.c > +++ b/drivers/gpu/drm/mxsfb/mxsfb_crtc.c > @@ -65,13 +65,11 @@ static int mxsfb_set_pixel_fmt(struct mxsfb_drm_private *mxsfb) You should probably drop the WARNING: comment in this function too. > switch (format) { > case DRM_FORMAT_RGB565: > dev_dbg(drm->dev, "Setting up RGB565 mode\n"); > - ctrl |= CTRL_SET_BUS_WIDTH(STMLCDIF_16BIT); > ctrl |= CTRL_SET_WORD_LENGTH(0); > ctrl1 |= CTRL1_SET_BYTE_PACKAGING(0xf); > break; > case DRM_FORMAT_XRGB8888: > dev_dbg(drm->dev, "Setting up XRGB8888 mode\n"); > - ctrl |= CTRL_SET_BUS_WIDTH(STMLCDIF_24BIT); > ctrl |= CTRL_SET_WORD_LENGTH(3); > /* Do not use packed pixels = one pixel per word instead. */ > ctrl1 |= CTRL1_SET_BYTE_PACKAGING(0x7); > @@ -89,6 +87,9 @@ static int mxsfb_set_pixel_fmt(struct mxsfb_drm_private *mxsfb) > > static void mxsfb_enable_controller(struct mxsfb_drm_private *mxsfb) > { > + struct drm_crtc *crtc = &mxsfb->pipe.crtc; > + struct drm_device *drm = crtc->dev; > + u32 bus_format = MEDIA_BUS_FMT_RGB888_1X24; So why do you move the bus width configuration from mxsfb_set_pixel_fmt() to here ? Is there any reason for it? > u32 reg; > > if (mxsfb->clk_disp_axi) > @@ -97,7 +98,28 @@ static void mxsfb_enable_controller(struct mxsfb_drm_private *mxsfb) > mxsfb_enable_axi_clk(mxsfb); > > /* If it was disabled, re-enable the mode again */ > - writel(CTRL_DOTCLK_MODE, mxsfb->base + LCDC_CTRL + REG_SET); > + reg = readl(mxsfb->base + LCDC_CTRL); Wouldn't it make more sense to cache the LCDC_CTRL content rather than doing R-M-W on it ? > + reg |= CTRL_DOTCLK_MODE; > + > + if (mxsfb->connector.display_info.num_bus_formats) > + bus_format = mxsfb->connector.display_info.bus_formats[0]; > + > + reg &= ~CTRL_BUS_WIDTH_MASK; > + switch (bus_format) { > + case MEDIA_BUS_FMT_RGB565_1X16: > + reg |= CTRL_SET_BUS_WIDTH(STMLCDIF_16BIT); > + break; > + case MEDIA_BUS_FMT_RGB666_1X18: > + reg |= CTRL_SET_BUS_WIDTH(STMLCDIF_18BIT); > + break; > + case MEDIA_BUS_FMT_RGB888_1X24: > + reg |= CTRL_SET_BUS_WIDTH(STMLCDIF_24BIT); > + break; > + default: > + dev_err(drm->dev, "Unknown media bus format %d\n", bus_format); > + break; > + } > + writel(reg, mxsfb->base + LCDC_CTRL); On MX6SX: Tested-by: Marek Vasut -- Best regards, Marek Vasut