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 <stefan at agner.ch>
> ---
> 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 <marex at denx.de>
--
Best regards,
Marek Vasut
