Messages in this thread | | | From | Adrian Ratiu <> | Subject | Re: [PATCH v6 1/8] drm: bridge: dw_mipi_dsi: add initial regmap infrastructure | Date | Fri, 17 Apr 2020 11:07:37 +0300 |
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On Thu, 16 Apr 2020, Enric Balletbo Serra <eballetbo@gmail.com> 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 > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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