linux-kernel - Re: [PATCH v2 2/3] tpm_tis: Use devm_ioremap

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Date:	Tue, 1 Dec 2015 13:46:23 -0700
From:	Jason Gunthorpe <jgunthorpe@...idianresearch.com>
To:	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>
Cc:	Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
	tpmdd-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
	Martin Wilck <Martin.Wilck@...fujitsu.com>,
	Peter Huewe <peterhuewe@....de>
Subject: Re: [PATCH v2 2/3] tpm_tis: Use devm_ioremap_resource

On Tue, Dec 01, 2015 at 08:52:17PM +0100, Uwe Kleine-König wrote:

> The issue I saw is: There are three(?) ways the tpm could be bound. If
> one of the succeeds, the other two are expected to fail. But in this
> case an error message, that the tpm failed to be bound is at least
> misleading.

My expectation is that the platform will never have a device that can
be bound to more than one and/or the driver core will prevent it (ie
if a PNP and ACPI driver claim the same ID the core should bind the
ACPI device only, not bind the ACPI device then downgrade to PNP and
try to bind the PNP device)

This issue pre-exists this patch. All this patch is doing is forcing
the tpm_tis to fail to bind instead of potentially running two drivers
on the same iorange at once.

The only case where this might not be true is if the user specifies
force. In this case, if forcing and there is acpi/pnp tpm at the same
address, then there will be a message failing the acpi/pnp bind. I
feel that is OK because it does indicate the user has done something
very questionable. (there is little reason to use force if acpi
already has the tpm at the same address range)

Jason
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