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

[Rasmus Villemoes <rasmus.villemoes@prevas.dk>]

On 01/02/2023 23.00, Marek Vasut wrote:
> On 1/30/23 13:45, Rasmus Villemoes wrote:
>> 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(?).
> 
> No, that samsung,esc-clock-frequency (should be some 10-20 MHz, based on
> your panel/bridge) and samsung,burst-clock-frequency (that's the HS
> clock) should go into board DT, as those are property of the attached
> panel/bridge.

OK.

But I simply can't make that match what I see in that branch. For
example, there's imx8mm-icore-mx8mm-ctouch2-of10.dts and
imx8mm-icore-mx8mm-edimm2.2.dts which both seem to have a ti,sn65dsi84
bridge, neither override the values defined in imx8mm.dtsi, which are

        samsung,burst-clock-frequency = <891000000>;
        samsung,esc-clock-frequency = <54000000>;

and that 891MHz value seems to be out of range for the dsi84 bridge -
under Recommended Operating Conditions, the data sheet says "DSI HS
clock input frequency", min 40, max 500 MHz.

There's also the "clk sys_pll1_266m can not be parent of clk media_apb".
Are you sure about those assigned-clocks and assigned-clock-parents
settings?

Rasmus


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