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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Paul Cercueil <paul@crapouillou.net>
Cc: Rob Herring <robh@kernel.org>,
	"Rafael J . Wysocki" <rafael@kernel.org>,
	David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
	Sam Ravnborg <sam@ravnborg.org>,
	list@opendingux.net, linux-kernel@vger.kernel.org,
	linux-mips@vger.kernel.org, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 2/2] gpu/drm: ingenic: Add workaround for disabled drivers
Date: Thu, 5 Aug 2021 21:35:34 +0200	[thread overview]
Message-ID: <YQw9hjZll4QmYVLX@kroah.com> (raw)
In-Reply-To: <20210805192110.90302-3-paul@crapouillou.net>

On Thu, Aug 05, 2021 at 09:21:09PM +0200, Paul Cercueil wrote:
> When the drivers of remote devices (e.g. HDMI chip) are disabled in the
> config, we want the ingenic-drm driver to be able to probe nonetheless
> with the other devices (e.g. internal LCD panel) that are enabled.
> 
> Signed-off-by: Paul Cercueil <paul@crapouillou.net>
> ---
>  drivers/gpu/drm/ingenic/ingenic-drm-drv.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> index d261f7a03b18..5e1fdbb0ba6b 100644
> --- a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> +++ b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> @@ -1058,6 +1058,18 @@ static int ingenic_drm_bind(struct device *dev, bool has_components)
>  	for (i = 0; ; i++) {
>  		ret = drm_of_find_panel_or_bridge(dev->of_node, 0, i, &panel, &bridge);
>  		if (ret) {
> +			/*
> +			 * Workaround for the case where the drivers for the
> +			 * remote devices are not enabled. When that happens,
> +			 * drm_of_find_panel_or_bridge() returns -EPROBE_DEFER
> +			 * endlessly, which prevents the ingenic-drm driver from
> +			 * working at all.
> +			 */
> +			if (ret == -EPROBE_DEFER) {
> +				ret = driver_deferred_probe_check_state(dev);
> +				if (ret == -ENODEV || ret == -ETIMEDOUT)
> +					continue;
> +			}

So you are mucking around with devices on other busses within this
driver?  What could go wrong?  :(

Please use the existing driver core functionality for this type of
thing, it is not unique, no need for this function to be called.

thanks,

greg k-h

  reply	other threads:[~2021-08-05 19:35 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-05 19:21 [PATCH 0/2] gpu/drm: ingenic: Handle " Paul Cercueil
2021-08-05 19:21 ` [PATCH 1/2] drivers core: Export driver_deferred_probe_check_state() Paul Cercueil
2021-08-05 19:34   ` Greg Kroah-Hartman
2021-08-05 19:21 ` [PATCH 2/2] gpu/drm: ingenic: Add workaround for disabled drivers Paul Cercueil
2021-08-05 19:35   ` Greg Kroah-Hartman [this message]
2021-08-05 20:05     ` Paul Cercueil
2021-08-06 10:17       ` Greg Kroah-Hartman
2021-08-06 11:01         ` Paul Cercueil
2021-08-10  9:35           ` Daniel Vetter
2021-08-10 10:33             ` Paul Cercueil
2021-08-10 10:59               ` Daniel Vetter
2021-08-10 11:58                 ` Paul Cercueil
2021-08-10  9:47           ` Greg Kroah-Hartman
2021-08-10 10:40             ` Paul Cercueil
2021-08-10 10:52               ` Daniel Vetter

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