tpm, tpm_tis: Enable interrupt test

The test for interrupts in tpm_tis_send() is skipped if the flag
TPM_CHIP_FLAG_IRQ is not set. Since the current code never sets the flag
initially the test is never executed.

Fix this by setting the flag in tpm_tis_gen_interrupt() right after
interrupts have been enabled and before the test is executed.
Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
Tested-by: Michael Niewöhner <linux@mniewoehner.de>
Tested-by: Jarkko Sakkinen <jarkko@kernel.org>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

drivers/char/tpm/tpm_tis_core.c

@@ -793,10 +793,15 @@ static void tpm_tis_gen_interrupt(struct tpm_chip *chip)
 	cap_t cap;
 	int ret;
 
+	chip->flags |= TPM_CHIP_FLAG_IRQ;
+
 	if (chip->flags & TPM_CHIP_FLAG_TPM2)
 		ret = tpm2_get_tpm_pt(chip, 0x100, &cap2, desc);
 	else
 		ret = tpm1_getcap(chip, TPM_CAP_PROP_TIS_TIMEOUT, &cap, desc, 0);
+
+	if (ret)
+		chip->flags &= ~TPM_CHIP_FLAG_IRQ;
 }
 
 /* Register the IRQ and issue a command that will cause an interrupt. If an