From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755777AbcLNKsF (ORCPT ); Wed, 14 Dec 2016 05:48:05 -0500 Received: from mail-out.m-online.net ([212.18.0.10]:52737 "EHLO mail-out.m-online.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755735AbcLNKsC (ORCPT ); Wed, 14 Dec 2016 05:48:02 -0500 X-Auth-Info: CDbi1udDRWIWDNNyZZSJ2+YnGjNtWaiehtXs2zF0mPo= Subject: Re: [PATCH v2] drm/mxsfb: use bus_format to determine LCD bus width To: Stefan Agner References: <20161214010241.26107-1-stefan@agner.ch> Cc: airlied@linux.ie, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org From: Marek Vasut Message-ID: <1958f3a8-1536-0d47-838e-7a0810076f78@denx.de> Date: Wed, 14 Dec 2016 08:52:19 +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: <20161214010241.26107-1-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 12/14/2016 02:02 AM, 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 Minor nits below. > --- > Changes in v2: > - Use seperate function mxsfb_set_bus_fmt > > drivers/gpu/drm/mxsfb/mxsfb_crtc.c | 33 +++++++++++++++++++++++++++++++-- > drivers/gpu/drm/mxsfb/mxsfb_regs.h | 1 + > 2 files changed, 32 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/mxsfb/mxsfb_crtc.c b/drivers/gpu/drm/mxsfb/mxsfb_crtc.c > index 4bcc8a3..956769b 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) > 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); > @@ -87,6 +85,35 @@ static int mxsfb_set_pixel_fmt(struct mxsfb_drm_private *mxsfb) > return 0; > } > > +static void mxsfb_set_bus_fmt(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; > + u32 reg; ^^^ this is uninitialized > + writel(CTRL_BUS_WIDTH_MASK, mxsfb->base + LCDC_CTRL + REG_CLR); > + > + if (mxsfb->connector.display_info.num_bus_formats) > + bus_format = mxsfb->connector.display_info.bus_formats[0]; > + > + switch (bus_format) { > + case MEDIA_BUS_FMT_RGB565_1X16: > + reg |= CTRL_SET_BUS_WIDTH(STMLCDIF_16BIT); ^^^ here you're doing operation on uninited value. > + 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 + REG_SET); What I was thinking might be better is to save the calculated LCD_CRTC value in mxsfb_drm_private , but maybe R-M-W is good enough after all? Two writes are IMO not great because it unnecessarily reconfigures the controller twice. > +} > + > static void mxsfb_enable_controller(struct mxsfb_drm_private *mxsfb) > { > u32 reg; > @@ -182,6 +209,8 @@ static void mxsfb_crtc_mode_set_nofb(struct mxsfb_drm_private *mxsfb) > > writel(vdctrl0, mxsfb->base + LCDC_VDCTRL0); > > + mxsfb_set_bus_fmt(mxsfb); > + > /* Frame length in lines. */ > writel(m->crtc_vtotal, mxsfb->base + LCDC_VDCTRL1); > > diff --git a/drivers/gpu/drm/mxsfb/mxsfb_regs.h b/drivers/gpu/drm/mxsfb/mxsfb_regs.h > index 31d62cd..66a6ba9 100644 > --- a/drivers/gpu/drm/mxsfb/mxsfb_regs.h > +++ b/drivers/gpu/drm/mxsfb/mxsfb_regs.h > @@ -44,6 +44,7 @@ > #define CTRL_DATA_SELECT (1 << 16) > #define CTRL_SET_BUS_WIDTH(x) (((x) & 0x3) << 10) > #define CTRL_GET_BUS_WIDTH(x) (((x) >> 10) & 0x3) > +#define CTRL_BUS_WIDTH_MASK (0x3 << 10) > #define CTRL_SET_WORD_LENGTH(x) (((x) & 0x3) << 8) > #define CTRL_GET_WORD_LENGTH(x) (((x) >> 8) & 0x3) > #define CTRL_MASTER (1 << 5) > -- Best regards, Marek Vasut