linux-kernel - Re: [PATCH] drm/sun4i: Fix exclusivity of the TCON clocks

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Message-ID: <20180312094434.uucwvqy6pykxpbl7@flea>
Date:   Mon, 12 Mar 2018 10:44:34 +0100
From:   Maxime Ripard <maxime.ripard@...tlin.com>
To:     megous@...ous.com
Cc:     dev@...ux-sunxi.org, Jernej Skrabec <jernej.skrabec@...l.net>,
        David Airlie <airlied@...ux.ie>, Chen-Yu Tsai <wens@...e.org>,
        "open list:DRM DRIVERS FOR ALLWINNER A10" 
        <dri-devel@...ts.freedesktop.org>,
        "moderated list:ARM/Allwinner sunXi SoC support" 
        <linux-arm-kernel@...ts.infradead.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/sun4i: Fix exclusivity of the TCON clocks

On Sat, Mar 10, 2018 at 12:05:11PM +0100, megous@...ous.com wrote:
> From: Ondrej Jirman <megous@...ous.com>
> 
> Currently the exclusivity is enabled when the rate is set by
> the mode setting functions. These functions are called by
> mode_set_nofb callback of drm_crc_helper. Then exclusivity
> is disabled when tcon is disabled by atomic_disable
> callback.
> 
> What happens is that mode_set_nofb can be called once when
> mode chnages, and afterwards the system can call atomic_enable
> and atomic_disable multiple times without further calls to
> mode_set_nofb.
> 
> This happens:
> 
> mode_set_nofb   - clk exclusivity is enabled
> atomic_enable
> atomic_disable  - clk exclusivity is disabled
> atomic_enable
> atomic_disable  - clk exclusivity is already disabled, leading to WARN
>                   in clk_rate_exclusive_put
> 
> Solution is to enable exclusivity in sun4i_tcon_channel_set_status.
> 
> Signed-off-by: Ondrej Jirman <megous@...ous.com>
> Cc: Jernej Skrabec <jernej.skrabec@...l.net>

Applied, thanks!
Maxime

-- 
Maxime Ripard, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com

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