Re: [PATCH v8 03/14] drm: bridge: Generalize Exynos-DSI driver into a Samsung DSIM bridge

From: Marek Vasut <marex@denx.de>
To: Jagan Teki <jagan@amarulasolutions.com>,
	Andrzej Hajda <andrzej.hajda@intel.com>,
	Inki Dae <inki.dae@samsung.com>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Joonyoung Shim <jy0922.shim@samsung.com>,
	Seung-Woo Kim <sw0312.kim@samsung.com>,
	Kyungmin Park <kyungmin.park@samsung.com>,
	Frieder Schrempf <frieder.schrempf@kontron.de>,
	Fancy Fang <chen.fang@nxp.com>,
	Tim Harvey <tharvey@gateworks.com>,
	Michael Nazzareno Trimarchi <michael@amarulasolutions.com>,
	Adam Ford <aford173@gmail.com>,
	Neil Armstrong <narmstrong@linaro.org>,
	Robert Foss <robert.foss@linaro.org>,
	Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
	Tommaso Merciai <tommaso.merciai@amarulasolutions.com>
Cc: Matteo Lisi <matteo.lisi@engicam.com>,
	dri-devel@lists.freedesktop.org,
	linux-samsung-soc@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	NXP Linux Team <linux-imx@nxp.com>,
	linux-amarula <linux-amarula@amarulasolutions.com>
Subject: Re: [PATCH v8 03/14] drm: bridge: Generalize Exynos-DSI driver into a Samsung DSIM bridge
Date: Thu, 17 Nov 2022 06:01:16 +0100	[thread overview]
Message-ID: <47ed3aae-308a-3b13-93c5-e31a3024f3a0@denx.de> (raw)
In-Reply-To: <20221110183853.3678209-4-jagan@amarulasolutions.com>

On 11/10/22 19:38, Jagan Teki wrote:

[...]

> +static int samsung_dsim_wait_for_hdr_fifo(struct samsung_dsim *dsi)
> +{
> +	int timeout = 2000;
> +
> +	do {
> +		u32 reg = samsung_dsim_read(dsi, DSIM_FIFOCTRL_REG);
> +
> +		if (!(reg & DSIM_SFR_HEADER_FULL))

Seems that unless I wait for DSIM_SFR_HEADER_EMPTY here, there may be 
some command transfer corruption if very short commands are transferred 
in rapid succession. This can be triggered with icn6211 driver for example.

> +			return 0;
> +
> +		if (!cond_resched())
> +			usleep_range(950, 1050);
> +	} while (--timeout);
> +
> +	return -ETIMEDOUT;
> +}

[...]

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