Revert "bus: mhi: core: Add support for reading MHI info from device"
authorJeffrey Hugo <quic_jhugo@quicinc.com>
Mon, 19 Feb 2024 18:07:48 +0000 (11:07 -0700)
committerManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Wed, 21 Feb 2024 05:52:25 +0000 (11:22 +0530)
commitf0397e27d1204a7e6581d140c2de7fd11383c6ba
tree88c064c97f53505cd2c900feb72f3744cb60d014
parentceeb64f41fe6a1eb9fc56d583983a81f8f3dd058
Revert "bus: mhi: core: Add support for reading MHI info from device"

This reverts commit 3316ab2b45f6bf4797d8d65b22fda3cc13318890.

The MHI spec owner pointed out that the SOC_HW_VERSION register is part
of the BHIe segment, and only valid on devices which implement BHIe.
Only a small subset of MHI devices implement BHIe so blindly accessing
the register for all devices is not correct. Also, since the BHIe
segment offset is not used when accessing the register, any
implementation which moves the BHIe segment will result in accessing
some other register.  We've seen that accessing this register on AIC100
which does not support BHIe can result in initialization failures.

We could try to put checks into the code to address these issues, but in
the roughly 4 years this functionality has existed, no one has used it.
Easier to drop this dead code and address the issues if anyone comes up
with a real world use for it.

Signed-off-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20240219180748.1591527-1-quic_jhugo@quicinc.com
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
drivers/bus/mhi/host/init.c
drivers/bus/mhi/host/internal.h
include/linux/mhi.h