> On 20. 8. 2022, at 21:45, Arminder Singh <arminders208@xxxxxxxxxxx> wrote: > > This is the first time I'm interacting with the Linux mailing lists, so > please don't eviscerate me *too much* if I get the formatting wrong. > Of course I'm always willing to take criticism and improve my formatting > in the future. > > This patch adds support for IRQs to the PASemi I2C controller driver. > This will allow for faster performing I2C transactions on Apple Silicon > hardware, as previously, the driver was forced to poll the SMSTA register > for a set amount of time. > > With this patchset the driver on Apple silicon hardware will instead wait > for an interrupt which will signal the completion of the I2C transaction. > The timeout value for this completion will be the same as the current > amount of time the I2C driver polls for. > > This will result in some performance improvement since the driver will be > waiting for less time than it does right now on Apple Silicon hardware. > > The patch right now will only enable IRQs for Apple Silicon I2C chips, > and only if it's able to successfully request the IRQ from the kernel. > > === Testing === > > This patch has been tested on both the mainline Linux kernel tree and > the Asahi branch (https://github.com/AsahiLinux/linux.git) on both an > M1 and M2 MacBook Air, and it compiles successfully as both a module and > built-in to the kernel itself. The patch in both trees successfully boots > to userspace without any hitch. > > I do not have PASemi hardware on hand unfortunately, so I'm unable to test > the impact of this patch on old PASemi hardware. This is also why I've > elected to do the IRQ request and enablement on the Apple platform driver > and not in the common file, as I'm not sure if PASemi hardware supports > IRQs. > > I also fixed a quick checkpatch warning on line 303. "i ++" is now "i++". > > Any and all critiques of the patch would be well appreciated. > > > > > Signed-off-by: Arminder Singh <arminders208@xxxxxxxxxxx> Thanks for the patch! Tested-by: Martin Povišer <povik+lin@xxxxxxxxxxx> on Mac mini (2020) with M1, with in-kernel WIP sound drivers. Some timing comparison on boot logs follows, three runs with and without the patch. With: [ 0.631034] ALSA device list: [ 0.631403] #0: Mac mini J274 integrated audio [ 0.625559] ALSA device list: [ 0.625997] #0: Mac mini J274 integrated audio [ 0.624561] ALSA device list: [ 0.624913] #0: Mac mini J274 integrated audio Without: [ 0.681599] ALSA device list: [ 0.682051] #0: Mac mini J274 integrated audio [ 0.677538] ALSA device list: [ 0.677968] #0: Mac mini J274 integrated audio [ 0.686037] ALSA device list: [ 0.686400] #0: Mac mini J274 integrated audio (After I collected these I realised I don’t know to what exactly the timing of the print is anchored, but anyway it still suggests there is speed-up.) Best, Martin
