linux-kernel - Re: [PATCH] tpm_tis: Re-enable interrupts upon resume

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Message-ID: <4D69050B.2050504@linux.vnet.ibm.com>
Date:	Sat, 26 Feb 2011 08:50:03 -0500
From:	Stefan Berger <stefanb@...ux.vnet.ibm.com>
To:	Jiri Slaby <jirislaby@...il.com>
CC:	preining@...ic.at,
	Linux kernel mailing list <linux-kernel@...r.kernel.org>,
	Rajiv Andrade <srajiv@...ux.vnet.ibm.com>,
	"debora@...ux.vnet.ibm.com" <debora@...ux.vnet.ibm.com>
Subject: Re: [PATCH] tpm_tis: Re-enable interrupts upon resume

On 02/26/2011 06:46 AM, Jiri Slaby wrote:
> On 02/22/2011 08:49 PM, Stefan Berger wrote:
>> Below patch applies to the tip of the git tree.
>>
>> This patch makes sure that if the TPM TIS interface is run in interrupt
>> mode (rather than polling mode) that the interrupts are enabled in the
>> TPM's interrupt enable register which may either have been cleared by
>> the TPM's TIS loosing its state during device sleep in ACPI S3 (suspend)
>> or by the BIOS, which upon resume sends a TPM_Startup() command to the
>> TPM, and may run the TPM in polling mode and leave the TIS interrupts
>> disabled once it transfers control to the OS again.
>>
>> Problem is, I don't currently have a machine running the TPM in
>> interrupt mode. I found this through a self-built TPM device model for
>> Qemu and SeaBIOS patches, where this does resolve a problem upon resume.
>>
>> You may want to check if your TPM runs with interrupts by doing
>>
>> cat /proc/interrupts | grep -i tpm
> No, this is empty output.
Ok. That's what most TPM seem to do now -- they run in polling mode.

   Stefan

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