On Thu, 16 Apr 2020, Enric Balletbo Serra <eballetbo@xxxxxxxxx>
wrote:
Hi Adrian,
[snip]
>>
>> +static void dw_mipi_dsi_get_hw_version(struct dw_mipi_dsi
>> *dsi) +{ + regmap_read(dsi->regs, DSI_VERSION,
>> &dsi->hw_version); + dsi->hw_version &= VERSION; + if
>> (!dsi->hw_version) + dev_err(dsi->dev, "Failed
>> to read DSI hw version register\n");
>
> Is this an error that should be ignored? If you can't get the
> HW version, probably, there is something wrong with your
> hardware so, don't you need to return an error?
>
After thinking a bit more about it, that error should be a
warning.
I added it because in some cases (for eg. if the peripheral
clock is disabled) the reads can return 0 which is obviously an
invalid version and the bridge will error in the next step when
not finding a layout.
If you'll error anyway, why wait? IIUC at this point the clock
*must* be enabled, and if not, something is wrong with the
driver, I don't see any advantage on delay the error. do you
have a use case where this is called and peripheral clock
disabled?
There should be no real use-case (maybe malfunctioning HW), and we
could error out here to catch driver bugs ASAP, so I'll go this
route then :)
Thank you, much appreciated!
So I'll make this a warning in v7 and explicitely mention that
reads version == 0 can be caused by a disabled pclk.
-- Enric
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