Re: [PATCH v12 00/18] drm: Add Samsung MIPI DSIM bridge

From: Alexander Stein <alexander.stein@ew.tq-group.com>
To: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Cc: Marek Vasut <marex@denx.de>,
	Jagan Teki <jagan@amarulasolutions.com>,
	linux-arm-kernel@lists.infradead.org,
	Laurent.pinchart@ideasonboard.com, aford173@gmail.com,
	andrzej.hajda@intel.com, dri-devel@lists.freedesktop.org,
	frieder.schrempf@kontron.de, inki.dae@samsung.com,
	kyungmin.park@samsung.com, linux-amarula@amarulasolutions.com,
	linux-arm-kernel@lists.infradead.org, linux-imx@nxp.com,
	linux-samsung-soc@vger.kernel.org, m.szyprowski@samsung.com,
	matteo.lisi@engicam.com, sw0312.kim@samsung.com,
	tharvey@gateworks.com
Subject: Re: [PATCH v12 00/18] drm: Add Samsung MIPI DSIM bridge
Date: Tue, 31 Jan 2023 08:27:45 +0100	[thread overview]
Message-ID: <4811510.31r3eYUQgx@steina-w> (raw)
In-Reply-To: <f6cea911-783c-f59d-503c-1576358ae7cb@prevas.dk>

Hi Rasmus,

Am Montag, 30. Januar 2023, 13:45:38 CET schrieb Rasmus Villemoes:
> On 27/01/2023 12.30, Marek Vasut wrote:
> > On 1/27/23 12:04, Jagan Teki wrote:
> >>> Thanks, but that's exactly what I'm doing, and I don't see any
> >>> modification of imx8mp.dtsi in that branch. I'm basically looking for
> >>> help to do the equivalent of
> >>> 
> >>>    88775338cd58 - arm64: dts: imx8mm: Add MIPI DSI pipeline
> >>>    f964f67dd6ee - arm64: dts: imx8mm: Add eLCDIF node support
> >>> 
> >>> for imx8mp in order to test those patches on our boards (we have two
> >>> variants).
> >> 
> >> Marek, any help here, thanks.
> > 
> > Try attached patch.
> 
> Thanks. I removed the lcdif2 and ldb nodes I had added from Alexander's
> patch (94e6197dadc9 in linux-next) in order to apply it. I get a couple
> of errors during boot:
> 
>   clk: /soc@0/bus@32c00000/mipi_dsi@32e60000: failed to reparent
> media_apb to sys_pll1_266m: -22
> 
> and enabling a pr_debug in clk_core_set_parent_nolock() shows that this
> is because
> 
>   clk_core_set_parent_nolock: clk sys_pll1_266m can not be parent of clk
> media_apb
> 
> Further, the mipi_dsi fails to probe due to
> 
>   /soc@0/bus@32c00000/mipi_dsi@32e60000: failed to get
> 'samsung,burst-clock-frequency' property
> 
> All other .dtsi files seem to have those samsung,burst-clock-frequency
> and samsung,esc-clock-frequency properties, so I suppose those should
> also go into the imx8mp.dtsi and are not something that the board .dts
> file should supply(?).
> 
> 
> [There's also some differences between your patch and Alexander's
> regarding the lcdif2 and ldb nodes, so while my lvds display still sorta
> works, I get
> 
>   fsl-ldb 32ec0000.blk-ctrl:lvds-ldb: Configured LDB clock (297000000
> Hz) does not match requested LVDS clock: 346500000 Hz
> 
> and the image is oddly distorted/shifted. But I suppose that's
> orthogonal to getting the lcdif1 -> mipi-dsi -> ... pipeline working.]

It seems my patch indicates exactly what's your problem here. Your clock rate 
configuration for LCDIF2 and LDB are not compatible (ratio 1:7). For now 
manual clock config is necessary in this case.
Check the clock tree in debugfs how your root clocks are configured and if it 
affects lcdif1 and lcdif2.

Best regards
Alexander

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