On 2020-11-11 14:06, Brad Campbell wrote:
Commit fff2d0f701e6 ("hwmon: (applesmc) avoid overlong udelay()")
introduced an issue whereby communication with the SMC became
unreliable with write errors like :
[ 120.378614] applesmc: send_byte(0x00, 0x0300) fail: 0x40
[ 120.378621] applesmc: LKSB: write data fail
[ 120.512782] applesmc: send_byte(0x00, 0x0300) fail: 0x40
[ 120.512787] applesmc: LKSB: write data fail
The original code appeared to be timing sensitive and was not reliable
with the timing changes in the aforementioned commit.
This patch re-factors the SMC communication to remove the timing
dependencies and restore function with the changes previously
committed. Logic changes based on inspection of the Apple SMC kext.
Tested on : MacbookAir6,2 MacBookPro11,1 iMac12,2, MacBookAir1,1,
MacBookAir3,1
Fixes: fff2d0f701e6 ("hwmon: (applesmc) avoid overlong udelay()")
Reported-by: Andreas Kemnade <andreas@xxxxxxxxxxxx>
Tested-by: Andreas Kemnade <andreas@xxxxxxxxxxxx> # MacBookAir6,2
Acked-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Brad Campbell <brad@xxxxxxxxxxxxxxx>
Signed-off-by: Henrik Rydberg <rydberg@xxxxxxxxxxx>
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Changelog :
v1 : Initial attempt
v2 : Address logic and coding style
v3 : Removed some debug hangover. Added tested-by. Modifications for MacBookAir1,1
v4 : Re-factored logic based on Apple driver. Simplified wait_status loop
v5 : Re-wrote status loop. Simplified busy check in send_byte(). Fixed formatting
Hi Brad,
This version is still working fine on the MBA1,1, at 50 reads per second.
Thanks,
Henrik
