linux-kernel - Re: [PATCH] omapfb: In omapfb_probe return -EPROBE_DEFER when display driver is not loaded yet

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Message-ID: <51DE6F19.6050606@ti.com>
Date:	Thu, 11 Jul 2013 14:08:49 +0530
From:	Archit Taneja <archit@...com>
To:	Pali Rohár <pali.rohar@...il.com>
CC:	Tomi Valkeinen <tomi.valkeinen@...com>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	<linux-omap@...r.kernel.org>, <linux-fbdev@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, Pavel Machek <pavel@....cz>,
	Aaro Koskinen <aaro.koskinen@....fi>,
	Tony Lindgren <tony@...mide.com>
Subject: Re: [PATCH] omapfb: In omapfb_probe return -EPROBE_DEFER when display
 driver is not loaded yet

Hi,

On Wednesday 10 July 2013 06:38 PM, Pali Rohár wrote:
> * On RX-51 probing for acx565akm driver is later then for omapfb which cause that omapfb probe fail and framebuffer is not working
> * EPROBE_DEFER causing that kernel try to probe for omapfb later again which fixing this problem
>
> * Without this patch display on Nokia RX-51 (N900) phone not working
>
> Signed-off-by: Pali Rohár <pali.rohar@...il.com>
> ---
>   drivers/video/omap2/omapfb/omapfb-main.c |    9 +++++++++
>   1 file changed, 9 insertions(+)
>
> diff --git a/drivers/video/omap2/omapfb/omapfb-main.c b/drivers/video/omap2/omapfb/omapfb-main.c
> index 856917b..93e7c84 100644
> --- a/drivers/video/omap2/omapfb/omapfb-main.c
> +++ b/drivers/video/omap2/omapfb/omapfb-main.c
> @@ -2419,6 +2419,15 @@ static int omapfb_probe(struct platform_device *pdev)
>   	if (omapdss_is_initialized() == false)
>   		return -EPROBE_DEFER;
>
> +	dssdev = NULL;
> +	for_each_dss_dev(dssdev) {
> +		if (!dssdev->driver) {
> +			dev_warn(&pdev->dev, "no driver for display: %s\n",
> +				dssdev->name);
> +			return -EPROBE_DEFER;

This will make omapfb probe defer till the time every panel has a 
driver. It's possible that all the panel driver modules are never 
interested by userspace. This will lead to the panels having drivers 
also not work.

I think Tomi was working on this, it was something like making omapfb 
defer only if the default display doesn't have a driver. We can wait for 
his comment.

Archit

> +		}
> +	}
> +
>   	if (pdev->num_resources != 0) {
>   		dev_err(&pdev->dev, "probed for an unknown device\n");
>   		r = -ENODEV;
>

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