On 11/17/2021 9:24 AM, Jeffrey Hugo wrote:
On 11/8/2021 12:06 PM, Hemant Kumar wrote:
Adding same comment in v2
On 11/8/2021 9:49 AM, Manivannan Sadhasivam wrote:
Some devices tend to trigger SYS_ERR interrupt while the host handling
SYS_ERR state of the device during power up. This creates a race
condition and causes a failure in booting up the device.
The issue is seen on the Sierra Wireless EM9191 modem during SYS_ERR
handling in mhi_async_power_up(). Once the host detects that the device
is in SYS_ERR state, it issues MHI_RESET and waits for the device to
process the reset request. During this time, the device triggers SYS_ERR
Device is not triggering the SYS_ERR interrupt, interrupt was
triggered due to MHI RESET was getting cleared by device.
Shouldn't the device state be RESET and not SYS_ERR at that point?
The device will enter SYS_ERR (and trigger an interrupt for that). Host
issues MHI_RESET. Device is expected to clear SYS_ERR and enter the
RESET state. Then the device clears MHI_RESET. Device can then trigger
an interrupt to signal the state change (per the updated spec).
Dmesg log was showing first sys err was triggered by device, as part of
sys error handling host was setting MHI_RESET and expecting to get BHI
Intvec. When BHI intvec was triggered by device, host handled it by
checking the MHI status register. MHi status was still showing SYS_ERR
being set (which was supposed to get cleared after host issuing MHI
RESET). Due to that host side bhi intvec threaded handler took diff path
to handle sys error again. This is what we are trying to avoid as we
think for some reason device is not behaving as per spec and either
setting sys err again or not clearing it by the time bhi intvec (for
reset clear) is handled by host.
I was going to add my reviewed-by, but I'm confused by your comment.
[..]
Thanks,
Hemant
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