Messages in this thread | | | Subject | Re: [RFC PATCH] soundwire: bus: Add flag to mark DPN_BlockCtrl1 as readonly | From | Srinivas Kandagatla <> | Date | Wed, 11 Mar 2020 11:30:58 +0000 |
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Thanks for the inputs
On 10/03/2020 15:53, Pierre-Louis Bossart wrote: > Hi Srinivas, > >>> > My recommendation would be to add a DisCo property stating the >>> WordLength value can be used by the bus code but not written to the >>> Slave device registers. >> >> Does something like "mipi-sdw-read-only-wordlength" as slave property, >> make sense? > > The properties can be handled at two levels. > > First, you'd want to change include/linux/soundwire/sdw.h, and add a new > field in > > struct sdw_dpn_prop { > u32 num; > u32 max_word; > u32 min_word; > u32 num_words; > u32 *words; > + bool read_only_wordlength; > > Once this is added, along with the code that bypasses the programming of > DPn_BlockCtrl1, the implementation has two choices: > > a) hard-code the field value in the codec driver.
This totally works for me.
> > b) read the property from firmware with the DisCo helpers. >
I would defer adding this for now till there is a real users for this.
> There is no requirement that all properties be read from firmware, and > if you look at existing code base sdw_slave_read_prop() is currently > unused, each codec implements its own .read_prop() callback. > > We really wanted to be pragmatic, and give the possibility to either > override bad firmware or extend incomplete firmware to avoid coupling OS > and firmware too much. If you foresee cases where this implementation > might vary and firmware distribution is not a problem, then a property > read would make sense. > > Just once procedural reminder that all 'mipi-sdw' properties are handled > by the MIPI software WG, so we'd need to have this property added in a > formal MIPI document update. > > I suggest you talk with Lior first on this.
Sure, I will talk to him.
> > Hope this helps > -Pierre
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