linux-kernel - [PATCH 5.4 11/78] tpm: Revert "tpm_tis_core: Turn on the TPM before probing IRQs"

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Date:   Tue, 14 Jan 2020 11:00:45 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jerry Snitselaar <jsnitsel@...hat.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Xiaoping Zhou <xiaoping.zhou@...el.com>,
        Stefan Berger <stefanb@...ux.ibm.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Subject: [PATCH 5.4 11/78] tpm: Revert "tpm_tis_core: Turn on the TPM before probing IRQs"

From: Stefan Berger <stefanb@...ux.ibm.com>

commit aa4a63dd981682b1742baa01237036e48bc11923 upstream.

There has been a bunch of reports (one from kernel bugzilla linked)
reporting that when this commit is applied it causes on some machines
boot freezes.

Unfortunately hardware where this commit causes a failure is not widely
available (only one I'm aware is Lenovo T490), which means we cannot
predict yet how long it will take to properly fix tpm_tis interrupt
probing.

Thus, the least worst short term action is to revert the code to the
state before this commit. In long term we need fix the tpm_tis probing
code to work on machines that Stefan's fix was supposed to fix.

Fixes: 21df4a8b6018 ("tpm_tis: reserve chip for duration of tpm_tis_core_init")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=205935
Cc: stable@...r.kernel.org
Cc: Jerry Snitselaar <jsnitsel@...hat.com>
Cc: Dan Williams <dan.j.williams@...el.com>
Tested-by: Dan Williams <dan.j.williams@...el.com>
Tested-by: Xiaoping Zhou <xiaoping.zhou@...el.com>
Signed-off-by: Stefan Berger <stefanb@...ux.ibm.com>
Reported-by: Jerry Snitselaar <jsnitsel@...hat.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/char/tpm/tpm_tis_core.c |    2 --
 1 file changed, 2 deletions(-)

--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -980,7 +980,6 @@ int tpm_tis_core_init(struct device *dev
 			goto out_err;
 		}
 
-		tpm_chip_start(chip);
 		if (irq) {
 			tpm_tis_probe_irq_single(chip, intmask, IRQF_SHARED,
 						 irq);
@@ -990,7 +989,6 @@ int tpm_tis_core_init(struct device *dev
 		} else {
 			tpm_tis_probe_irq(chip, intmask);
 		}
-		tpm_chip_stop(chip);
 	}
 
 	rc = tpm_chip_register(chip);