Bug 199105

Summary: Cherry trail: sdhci-acpi not recognising eMMC (with commit that stopped it working)
Product: Drivers Reporter: Luke Ross (luke)
Component: MMC/SDAssignee: drivers_mmc-sd
Status: RESOLVED CODE_FIX    
Severity: normal CC: regressions
Priority: P1    
Hardware: x86-64   
OS: Linux   
Kernel Version: 4.16-rc5 Subsystem:
Regression: No Bisected commit-id:
Attachments: dmesg
/proc/interrupts
grep -H . /sys/kernel/irq/0/*

Description Luke Ross 2018-03-13 11:24:33 UTC 
I have an Intel Cherry-Trail based tablet which runs a 4.13 kernel without issue. It has two devices bound to sdhci-acpi - an internal 32GB eMMC (mmc0) and an SD card slot (mmc1).

Booting on 4.16-rc series kernels results in an error -22 on loading sdhci-acpi and so the eMMC is not available and the machine cannot get past the initramfs.

I have tracked this issue down to commit 1b7ba57ecc864173ef42fff7f8c2e9a880b42bd2 :

"mmc: sdhci-acpi: Handle return value of platform_get_irq"

Reverting this change and replacing it with a dev_err to log host->irq reveals that host->irq is being set to zero - however the eMMC works fine despite the apparent lack of IRQ - the machine continues to boot normally and is perfectly usable.

Under the working 4.13 kernel, both mmc0 and mmc1 are listed as using "ADMA" transfer - /proc/interrupts reveals that mmc1 (the slot) does have an interrupt but mmc0 (the on-board eMMC) doesn't.

Is is possible for the eMMC to not require an interrupt? It appears to function fine without one on both the 4.13 kernel and the patched 4.16-rc kernel.
Comment 1 The Linux kernel's regression tracker (Thorsten Leemhuis) 2018-03-19 10:41:13 UTC 
JFYI: I added this report to the list of regressions in 4.16.
Comment 2 The Linux kernel's regression tracker (Thorsten Leemhuis) 2018-03-19 10:43:44 UTC 
A lot of kernel developer do not use bugzilla, thus you shoul report your issue by mail. Best way in this case: Contact the developers that handled 1b7ba57ecc864173ef42fff7f8c2e9a880b42bd2:
   Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
    Acked-by: Adrian Hunter <adrian.hunter@intel.com>
    Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Also CC lkml and linux-mmc@vger.kernel.org please.
Comment 3 Luke Ross 2018-03-21 08:54:46 UTC 
Created attachment 274833 [details]
dmesg
Comment 4 Luke Ross 2018-03-21 08:55:13 UTC 
Created attachment 274835 [details]
/proc/interrupts
Comment 5 Luke Ross 2018-03-21 08:55:43 UTC 
Created attachment 274837 [details]
grep -H . /sys/kernel/irq/0/*
Comment 6 Luke Ross 2018-03-21 10:19:48 UTC 
A patch to fix this has been applied to the linux-mmc fixes branch, commit 	d58ac803cfbb92ede501409dd6afe9abb111d4f1 - "mmc: sdhci-acpi: Fix IRQ 0". I will test this patch (to double-check) in the next day or two.
Comment 7 Luke Ross 2018-03-21 22:34:14 UTC 
d58ac803cfbb92ede501409dd6afe9abb111d4f1 verified on the tablet in question.