Subject: RE: dt-bindings: display: xlnx: mixer: Inconsistent pixel format terminology in dt docs

From: [email-masked] (Hyun Kwon)
Date: Thu, 20 Aug 2020 16:38:18 -0700

Hi Kenneth,

> -----Original Message-----
> From: Kenneth Sloat <[email-masked]>
> Sent: Thursday, August 20, 2020 2:18 PM
> To: Hyun Kwon <[email-masked]>; [email-masked]
> Cc: Michal Simek <[email-masked]>; [email-masked]; linux-
> [email-masked]; [email-masked];
> [email-masked]; [email-masked];
> [email-masked]
> Subject: dt-bindings: display: xlnx: mixer: Inconsistent pixel format terminology
> in dt docs
> 
> Hello,
> 
> The Xilinx Video mixer IP uses the DRM fourcc string as a device tree binding in
> order to describe the format for a specific DRM layer/plane. Currently, in the
> device tree doc in
> "Documentation/devicetree/bindings/dma/xilinx/xilinx_frmbuf.txt" there is a list
> called "VIDEO FORMATS" with a table containing "Mixer IP Format" and
> associated "Driver supported Format String" (fourcc). In general, this table is not
> helpful, because "Mixer IP Format" does not match the Xilinx IP datasheet
> terminology for formats but rather some other commonly used nomenclature.
> This is also inconsistent from other Xilinx dts binding docs which specify the
> actual correct IP name and at times list other format nomenclature where
> helpful (i.e. xilinx_frmbuf.txt)
> 
> My suggestion is to remove the current "Mixer IP Format" strings in the doc and
> replace them with the actual IP names in the datasheet (which also match those
> used in Xilinx's Vivado FPGA tool). Otherwise, the programmer must cross
> reference other dts documentation or the code in order to figure these out. I am
> happy to provide a patch for this but wanted to throw out the suggestion first.

I agree. The bindings should be in sync with datasheet and not rely on
software definitions. Since the driver is only in Xilinx vendor tree,
please send directly to [email-masked].

Thanks!

-hyun

> Thanks
> Sincerely,
> Ken Sloat

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