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f0afba4042
The failure paths in tpm_tis_spi_transfer() do not deactivate
chip select. Send an empty message (cs_select == 0) to overcome
this.
The patch is tested by two ways.
One way needs to touch hardware:
1. force pull MISO pin down to GND, it emulates a forever
'WAIT' timing.
2. probe cs pin by an oscilloscope.
3. load tpm_tis_spi.ko.
After loading, dmesg prints:
"probe of spi0.0 failed with error -110"
and oscilloscope shows cs pin goes high(deactivated) after
the failure. Before the patch, cs pin keeps low.
Second way is by writing a fake spi controller.
1. implement .transfer_one method, fill all rx buf with 0.
2. implement .set_cs method, print the state of cs pin.
we can see cs goes high after the failure.
Signed-off-by: Peijie Shao <shaopeijie@cestc.cn>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Linux kernel
============
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