linux-kernel - Re: [PATCH] ACPI/IORT: Fix iort_node_get

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Message-ID: <20170106094811.GA8587@red-moon>
Date:   Fri, 6 Jan 2017 09:48:26 +0000
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     Sinan Kaya <okaya@...eaurora.org>
Cc:     linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
        Hanjun Guo <hanjun.guo@...aro.org>,
        Tomasz Nowicki <tn@...ihalf.com>,
        Nate Watterson <nwatters@...eaurora.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>
Subject: Re: [PATCH] ACPI/IORT: Fix iort_node_get_id() mapping entries
 indexing

On Thu, Jan 05, 2017 at 01:37:22PM -0500, Sinan Kaya wrote:
> On 1/5/2017 1:29 PM, Lorenzo Pieralisi wrote:
> > iort_node_get_id() takes an index as input to refer to a specific
> > mapping entry in the mapping array to retrieve the id at a specific
> > index provided the index is below the total mapping count; currently the
> > index is used to retrieve the mapping value from the correct entry but
> > not to dereference the correct entry while retrieving the mapping
> > output_reference (ie IORT parent pointer), which consequently always
> > resolves to the output_reference of the first entry in the mapping
> > array.
> 
> Maybe, irrelevant but I'm going to throw it out.
> 
> Can we somehow break these multiple input and multiple output single
> function into smaller and manageable pieces while we are fixing a bug
> on it?

No. This is a fix for code currently in the kernel that is going
to be released in a few weeks, it is not a clean-up, please let me
know if it works on your platforms.

> These functions seem to do N different things when an input is present
> or not. 
> 
> I got lost in these function when implementing ITS->SMMU->NC use case.

Hanjun is carrying out the clean-up of the mapping functions as part of
its platform MSIs patchset, I followed up on that already to achieve
what you request above.

Thanks,
Lorenzo