Hello Brian, On 08/20/2015 11:54 PM, Brian Norris wrote: > On Thu, Aug 20, 2015 at 09:07:16AM +0200, Javier Martinez Canillas wrote: >> The SPI core always reports the MODALIAS uevent as "spi:<modalias>" >> regardless of the mechanism that was used to register the device >> (i.e: OF or board code) and the table that is used later to match >> the driver with the device (i.e: SPI id table or OF match table). >> >> So drivers needs to export the SPI id table and this be built into >> the module or udev won't have the necessary information to autoload >> the needed driver module when the device is added. >> >> But this means that OF-only drivers needs to have both OF and SPI id >> tables that have to be kept in sync and also the dev node compatible >> manufacturer prefix is stripped when reporting the MODALIAS. Which can >> lead to issues if two vendors use the same SPI device name for example. >> >> To avoid the above, the SPI core behavior may be changed in the future >> to not require an SPI device table for OF-only drivers and report the >> OF module alias. So, it's better to also export the OF table even when >> is unused now to prevent breaking module loading when the core changes. >> >> Signed-off-by: Javier Martinez Canillas <jav...@osg.samsung.com> > > I appreciate the context for the whole problem here, but this commit > subject mostly doesn't apply to this driver, and it deson't seem to > match the problem this is solving. As I see it, the patch description > for this patch should be more like: > > "The OF ID table is used for auto-probing the device, but it is not > exported to the module device table. That means this driver won't > autoload when built as a module. > > Export the OF ID table to fix that. > > (insert some reference to the larger issue here)" > > Do you want to rewrite the message, shall I just prepend my > modifications, or am I off-base? >
Well, I believe my commit message is more accurate than yours :-) I mean, right now the OF modalias information is not really used neither by the SPI core since always MODALIAS=spi:foo is reported nor by user space since the MODALIAS uevent will never match the OF exported modalias. So this patch really is a no-op right now and is not fixing anything. As long as the driver has a MODULE_DEVICE_TABLE(spi,...), things will work without a MODULE_DEVICE_TABLE(of,...). However, this patch is needed to avoid breaking module autoloading in the future once RFC patch 18/18 is applied and the SPI core is changed to report a MODALIAS=of:N*T*Cfoo,bar for SPI devices registered by OF. Having said that, I will of course re-spin the patch and write a commit message that you agree on. So I'll be happy to trim it down if is providing too much content or is not correct. I just don't think your suggestion better matches reality than mine. Best regards, -- Javier Martinez Canillas Open Source Group Samsung Research America -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
