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Message-ID: <CABjd4Yxrk3hXnB5f6u+1HcJjymDZbtQ1F1HXkZ2dzF3dwCrWhg@mail.gmail.com>
Date: Sat, 18 May 2013 17:28:54 +0400
From: Alexey Charkov <alchark@...il.com>
To: "VT8500/WM8505 Linux Kernel"
<vt8500-wm8505-linux-kernel@...glegroups.com>
Cc: Florian Tobias Schandinat <FlorianSchandinat@....de>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
tomi.valkeinen@...com,
"linux-fbdev@...r.kernel.org" <linux-fbdev@...r.kernel.org>,
Tony Prisk <linux@...sktech.co.nz>
Subject: Re: [PATCH 4/4] fb: vt8500: Add VGA output support to wm8505fb driver.
2013/5/18 Tony Prisk <linux@...sktech.co.nz>:
> The APC8750 does not support an LCD panel, but provides a VGA connector.
> This patch adds support for the VGA interface, and defines an optional
> devicetree property to specify the output interface. The default if not
> specified is LCD for backward compatibility.
>
> Signed-off-by: Tony Prisk <linux@...sktech.co.nz>
> ---
> .../devicetree/bindings/video/wm,wm8505-fb.txt | 5 ++++
> drivers/video/wm8505fb.c | 31 ++++++++++++++++++--
> 2 files changed, 34 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/video/wm,wm8505-fb.txt b/Documentation/devicetree/bindings/video/wm,wm8505-fb.txt
> index 601416c..9f1d648 100644
> --- a/Documentation/devicetree/bindings/video/wm,wm8505-fb.txt
> +++ b/Documentation/devicetree/bindings/video/wm,wm8505-fb.txt
> @@ -7,6 +7,10 @@ Required properties:
> - bits-per-pixel : bit depth of framebuffer (16 or 32)
> - clocks : phandle to DVO clock
>
> +Optional properties:
> +- output-interface : the interface the fb should output on. Valid values are
> + "lcd" or "vga". If not specified, the default is "lcd".
> +
> Required subnodes:
> - display-timings: see display-timing.txt for information
>
> @@ -17,6 +21,7 @@ Example:
> reg = <0xd8051700 0x200>;
> bits-per-pixel = <16>;
> clocks = <&clkdvo>;
> + output-interface = "vga";
>
> display-timings {
> native-mode = <&timing0>;
> diff --git a/drivers/video/wm8505fb.c b/drivers/video/wm8505fb.c
> index f8bffc2..d1f7f33 100644
> --- a/drivers/video/wm8505fb.c
> +++ b/drivers/video/wm8505fb.c
> @@ -130,12 +130,17 @@
>
> #define to_wm8505fb_info(__info) container_of(__info, \
> struct wm8505fb_info, fb)
> +
> +#define INTERFACE_LCD 1
> +#define INTERFACE_VGA 2
> +
> struct wm8505fb_info {
> struct fb_info fb;
> void __iomem *regbase;
> unsigned int contrast;
> struct device *dev;
> struct clk *clk_dvo;
> + int interface;
> };
>
>
> @@ -158,7 +163,11 @@ static int wm8505fb_init_hw(struct fb_info *info)
> * 0x31C sets the correct color mode (RGB565) for WM8650
> * Bit 8+9 (0x300) are ignored on WM8505 as reserved
> */
> - writel(0x31c, fbi->regbase + REG_GOVRH_YUVRGB);
> + if (fbi->interface == INTERFACE_VGA)
> + writel(0x338, fbi->regbase + REG_GOVRH_YUVRGB);
> + else
> + writel(0x31c, fbi->regbase + REG_GOVRH_YUVRGB);
> +
> writel(1, fbi->regbase + REG_GOVRH_DVO_PIX);
Tony,
Would it be possible to also define known bit offsets for those
registers, while you are at this? It would probably reduce the black
magic quite a bit :)
> /* Virtual buffer size */
> @@ -167,7 +176,12 @@ static int wm8505fb_init_hw(struct fb_info *info)
>
> /* black magic ;) */
> writel(0xf, fbi->regbase + REG_GOVRH_FHI);
> - writel(4, fbi->regbase + REG_GOVRH_DVO_SET);
> +
> + if (fbi->interface == INTERFACE_VGA)
> + writel(0xe, fbi->regbase + REG_GOVRH_DVO_SET);
> + else
> + writel(4, fbi->regbase + REG_GOVRH_DVO_SET);
I don't remember if HDMI is yet another option for this register or
not... If it is, it would probably warrant defining fbi->interface as
an enum and changing this if-else into a switch statement to let the
compiler add its checks/warnings.
> writel(1, fbi->regbase + REG_GOVRH_MIF);
> writel(1, fbi->regbase + REG_GOVRH_REG_STS);
>
> @@ -194,11 +208,15 @@ static int wm8505fb_set_timing(struct fb_info *info)
> writel(h_end, fbi->regbase + REG_GOVRH_ACTPX_END);
> writel(h_all, fbi->regbase + REG_GOVRH_H_ALLPXL);
> writel(h_sync, fbi->regbase + REG_GOVRH_HDMI_HSYNW);
> + if (fbi->interface == INTERFACE_VGA)
> + writel(h_sync, fbi->regbase + REG_GOVRH_VGA_HSYNW);
Will it misbehave on LCD if you write to the VGA register unconditionally?
> writel(v_start, fbi->regbase + REG_GOVRH_ACTLN_BG);
> writel(v_end, fbi->regbase + REG_GOVRH_ACTLN_END);
> writel(v_all, fbi->regbase + REG_GOVRH_V_ALLLN);
> writel(v_sync, fbi->regbase + REG_GOVRH_HDMI_VBISW);
> + if (fbi->interface == INTERFACE_VGA)
> + writel(info->var.pixclock, fbi->regbase + REG_GOVRH_VGA_VSYNW);
Same here. I would assume that setting the pixclock should not hurt
LCD, which would then simplify the code a little.
Thanks,
Alexey
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