Re: [PATCH v4] omap4-fb: add driver

From: Alexander Aring <alex.aring@gmail.com>
To: Christoph Fritz <chf.fritz@googlemail.com>
Cc: barebox@lists.infradead.org
Subject: Re: [PATCH v4] omap4-fb: add driver
Date: Fri, 14 Jun 2013 08:29:11 +0200	[thread overview]
Message-ID: <20130614062910.GA10743@x61s.8.8.8.8> (raw)
In-Reply-To: <1371163239.4055.180.camel@mars>

Hi,

On Fri, Jun 14, 2013 at 12:40:39AM +0200, Christoph Fritz wrote:
> This patch adds omap4 display controller support.
> 
> Signed-off-by: Christoph Fritz <chf.fritz@googlemail.com>
> ---
> changes since v2:
>         - use dev_request_mem_region_by_name()
> changes since v3:
> 	- remove register struct
> 	- use uncached screen_base
> ---
>  arch/arm/mach-omap/Makefile                |    1 +
>  arch/arm/mach-omap/include/mach/omap4-fb.h |   46 +++
>  arch/arm/mach-omap/omap4_fb.c              |   27 ++
>  drivers/video/Kconfig                      |    8 +
>  drivers/video/Makefile                     |    1 +
>  drivers/video/omap4.c                      |  505 ++++++++++++++++++++++++++++
>  drivers/video/omap4.h                      |  179 ++++++++++
>  7 files changed, 767 insertions(+)
>  create mode 100644 arch/arm/mach-omap/include/mach/omap4-fb.h
>  create mode 100644 arch/arm/mach-omap/omap4_fb.c
>  create mode 100644 drivers/video/omap4.c
>  create mode 100644 drivers/video/omap4.h
> 
> diff --git a/arch/arm/mach-omap/Makefile b/arch/arm/mach-omap/Makefile
> index 94e42c6..e70ddbd 100644
> --- a/arch/arm/mach-omap/Makefile
> +++ b/arch/arm/mach-omap/Makefile
> @@ -28,6 +28,7 @@ obj-$(CONFIG_OMAP3_CLOCK_CONFIG) += omap3_clock.o
>  pbl-$(CONFIG_OMAP3_CLOCK_CONFIG) += omap3_clock.o
>  obj-$(CONFIG_OMAP_GPMC) += gpmc.o devices-gpmc-nand.o
>  obj-$(CONFIG_SHELL_NONE) += xload.o
> +obj-$(CONFIG_DRIVER_VIDEO_OMAP4) += omap4_fb.o
>  obj-$(CONFIG_I2C_TWL6030) += omap4_twl6030_mmc.o
>  obj-$(CONFIG_OMAP4_USBBOOT) += omap4_rom_usb.o
>  obj-y += gpio.o
> diff --git a/arch/arm/mach-omap/include/mach/omap4-fb.h b/arch/arm/mach-omap/include/mach/omap4-fb.h
> new file mode 100644
> index 0000000..5c0a54b
> --- /dev/null
> +++ b/arch/arm/mach-omap/include/mach/omap4-fb.h
> @@ -0,0 +1,46 @@

...

> +	fb_write(1, fbi->dispc, O4_DISPC_VID1_PIXEL_INC);
> +
> +	fb_write(0xfff, fbi->dispc, O4_DISPC_VID1_PRELOAD);
> +
> +	fb_write(DSS_DISPC_VIDn_ATTRIBUTES_VIDFORMAT(fmt) |
> +			 DSS_DISPC_VIDn_ATTRIBUTES_VIDBURSTSIZE_8x128 |
> +			 DSS_DISPC_VIDn_ATTRIBUTES_ZORDERENABLE |
> +			 DSS_DISPC_VIDn_ATTRIBUTES_CHANNELOUT2_SECONDARY_LCD,
> +			 fbi->dispc, O4_DISPC_VID1_ATTRIBUTES);
> +
> +	while (fb_read(fbi->dispc, O4_DISPC_CONTROL2) & DSS_DISPC_CONTROL_GOLCD)
> +		;			/* noop */

For busy waiting on statusbits I would prefer a mechanism like this:

start = get_time_ns();
while (condition) {
...
	if (is_timeout(start, waiting_time)) {
		dev_err(dev, "foo"
		return -ETIMEOUT;
	}
	mdelay(interval);
...
}

I mean it avoid deadlocks in barebox and it's better to start linux
without a display instead of a deadlock in barebox.
On the other hand you need a waiting_time which works with all displays
together. Don't know if there any hardware dependency.

}
> +
> +	fb_write(fb_read(fbi->dispc, O4_DISPC_CONTROL2) |
> +		 DSS_DISPC_CONTROL_GOLCD,
> +		 fbi->dispc, O4_DISPC_CONTROL2);
> +
> +	fbi->cur_display = new_display;
> +	info->xres = mode->xres;
> +	info->yres = mode->yres;
> +
> +	rc = 0;
> +
> +out:
> +	return rc;
> +}

...

> +
> +	omap4fb_reset(fbi);
> +
> +	dev_add_param(fbi->dev, "bootargs", NULL, NULL, 0);
> +
Jean-Christophe PLAGNIOL-VILLARD said why we need this here in the last
mails. I don't saw any answer to this and asking myself... what do this
function?

Regards
Alex

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