linux-kernel - [PATCH for-linus-v5.5-rc6 3/3] tpm: Revert "tpm_tis_core: Turn on the TPM before probing IRQ's"

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Date:   Sat,  4 Jan 2020 01:29:34 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     linux-integrity@...r.kernel.org
Cc:     Stefan Berger <stefanb@...ux.ibm.com>, stable@...r.kernel.org,
        Jerry Snitselaar <jsnitsel@...hat.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Xiaoping Zhou <xiaoping.zhou@...el.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Peter Huewe <peterhuewe@....de>,
        Jason Gunthorpe <jgg@...pe.ca>, Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH for-linus-v5.5-rc6 3/3] tpm: Revert "tpm_tis_core: Turn on the TPM before probing IRQ's"

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

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

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 5dc52c4e2292..27c6ca031e23 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -1059,7 +1059,6 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
 			goto out_err;
 		}
 
-		tpm_chip_start(chip);
 		if (irq) {
 			tpm_tis_probe_irq_single(chip, intmask, IRQF_SHARED,
 						 irq);
@@ -1069,7 +1068,6 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
 		} else {
 			tpm_tis_probe_irq(chip, intmask);
 		}
-		tpm_chip_stop(chip);
 	}
 
 	rc = tpm_chip_register(chip);
-- 
2.20.1