Re: [PATCH 05/21] drm: mxsfb: Clarify format and bus width configuration

From: Stefan Agner <stefan@agner.ch>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Marek Vasut <marex@denx.de>,
	kernel@pengutronix.de, dri-devel@lists.freedesktop.org,
	linux-imx@nxp.com
Subject: Re: [PATCH 05/21] drm: mxsfb: Clarify format and bus width configuration
Date: Mon, 23 Mar 2020 22:42:44 +0100	[thread overview]
Message-ID: <49c64da57bd2e9561e36320fdc3881d3@agner.ch> (raw)
In-Reply-To: <20200309195216.31042-6-laurent.pinchart@ideasonboard.com>

On 2020-03-09 20:52, Laurent Pinchart wrote:
> Replace the convoluted way to set the format and bus width through
> difficult to read macros with more explicit ones. Also remove the
> outdated comment related to the limitations on bus width setting as it

Nice catch.

> doesn't apply anymore (the bus width can be specified through the
> display_info bus format).

Reviewed-by: Stefan Agner <stefan@agner.ch>

> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> ---
>  drivers/gpu/drm/mxsfb/mxsfb_crtc.c | 17 +++++------------
>  drivers/gpu/drm/mxsfb/mxsfb_regs.h | 17 ++++++++---------
>  2 files changed, 13 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
> b/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
> index b69ace8bf526..8b6339316929 100644
> --- a/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
> +++ b/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
> @@ -52,13 +52,6 @@ static int mxsfb_set_pixel_fmt(struct
> mxsfb_drm_private *mxsfb)
>  
>  	ctrl = CTRL_BYPASS_COUNT | CTRL_MASTER;
>  
> -	/*
> -	 * WARNING: The bus width, CTRL_SET_BUS_WIDTH(), is configured to
> -	 * match the selected mode here. This differs from the original
> -	 * MXSFB driver, which had the option to configure the bus width
> -	 * to arbitrary value. This limitation should not pose an issue.
> -	 */
> -
>  	/* CTRL1 contains IRQ config and status bits, preserve those. */
>  	ctrl1 = readl(mxsfb->base + LCDC_CTRL1);
>  	ctrl1 &= CTRL1_CUR_FRAME_DONE_IRQ_EN | CTRL1_CUR_FRAME_DONE_IRQ;
> @@ -66,12 +59,12 @@ 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_WORD_LENGTH(0);
> +		ctrl |= CTRL_WORD_LENGTH_16;
>  		ctrl1 |= CTRL1_SET_BYTE_PACKAGING(0xf);
>  		break;
>  	case DRM_FORMAT_XRGB8888:
>  		dev_dbg(drm->dev, "Setting up XRGB8888 mode\n");
> -		ctrl |= CTRL_SET_WORD_LENGTH(3);
> +		ctrl |= CTRL_WORD_LENGTH_24;
>  		/* Do not use packed pixels = one pixel per word instead. */
>  		ctrl1 |= CTRL1_SET_BYTE_PACKAGING(0x7);
>  		break;
> @@ -104,13 +97,13 @@ static void mxsfb_set_bus_fmt(struct
> mxsfb_drm_private *mxsfb)
>  	reg &= ~CTRL_BUS_WIDTH_MASK;
>  	switch (bus_format) {
>  	case MEDIA_BUS_FMT_RGB565_1X16:
> -		reg |= CTRL_SET_BUS_WIDTH(STMLCDIF_16BIT);
> +		reg |= CTRL_BUS_WIDTH_16;
>  		break;
>  	case MEDIA_BUS_FMT_RGB666_1X18:
> -		reg |= CTRL_SET_BUS_WIDTH(STMLCDIF_18BIT);
> +		reg |= CTRL_BUS_WIDTH_18;
>  		break;
>  	case MEDIA_BUS_FMT_RGB888_1X24:
> -		reg |= CTRL_SET_BUS_WIDTH(STMLCDIF_24BIT);
> +		reg |= CTRL_BUS_WIDTH_24;
>  		break;
>  	default:
>  		dev_err(drm->dev, "Unknown media bus format %d\n", bus_format);
> diff --git a/drivers/gpu/drm/mxsfb/mxsfb_regs.h
> b/drivers/gpu/drm/mxsfb/mxsfb_regs.h
> index 78e6cb754712..8ebb52bb1b46 100644
> --- a/drivers/gpu/drm/mxsfb/mxsfb_regs.h
> +++ b/drivers/gpu/drm/mxsfb/mxsfb_regs.h
> @@ -34,11 +34,15 @@
>  #define CTRL_VSYNC_MODE			BIT(18)
>  #define CTRL_DOTCLK_MODE		BIT(17)
>  #define CTRL_DATA_SELECT		BIT(16)
> -#define CTRL_SET_BUS_WIDTH(x)		(((x) & 0x3) << 10)
> -#define CTRL_GET_BUS_WIDTH(x)		(((x) >> 10) & 0x3)
> +#define CTRL_BUS_WIDTH_16		(0 << 10)
> +#define CTRL_BUS_WIDTH_8		(1 << 10)
> +#define CTRL_BUS_WIDTH_18		(2 << 10)
> +#define CTRL_BUS_WIDTH_24		(3 << 10)
>  #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_WORD_LENGTH_16		(0 << 8)
> +#define CTRL_WORD_LENGTH_8		(1 << 8)
> +#define CTRL_WORD_LENGTH_18		(2 << 8)
> +#define CTRL_WORD_LENGTH_24		(3 << 8)
>  #define CTRL_MASTER			BIT(5)
>  #define CTRL_DF16			BIT(3)
>  #define CTRL_DF18			BIT(2)
> @@ -91,9 +95,4 @@
>  #define MXSFB_MAX_XRES			0xffff
>  #define MXSFB_MAX_YRES			0xffff
>  
> -#define STMLCDIF_8BIT  1 /* pixel data bus to the display is of 8 bit width */
> -#define STMLCDIF_16BIT 0 /* pixel data bus to the display is of 16 bit width */
> -#define STMLCDIF_18BIT 2 /* pixel data bus to the display is of 18 bit width */
> -#define STMLCDIF_24BIT 3 /* pixel data bus to the display is of 24 bit width */
> -
>  #endif /* __MXSFB_REGS_H__ */
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