linux-kernel - Re: screen rotation flipped in 4.8-rc

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Date:   Wed, 31 Aug 2016 17:48:40 -0700
From:   Matt Ranostay <mranostay@...il.com>
To:     Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux@...encehorizons.net" <linux@...encehorizons.net>,
        "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
        "jic23@...nel.org" <jic23@...nel.org>,
        "hadess@...ess.net" <hadess@...ess.net>
Subject: Re: screen rotation flipped in 4.8-rc

On Wed, Aug 31, 2016 at 3:53 PM, Srinivas Pandruvada
<srinivas.pandruvada@...ux.intel.com> wrote:
> On Wed, 2016-08-31 at 13:43 -0700, Matt Ranostay wrote:
>> On Wed, Aug 31, 2016 at 1:29 PM, Pandruvada, Srinivas
>> <srinivas.pandruvada@...el.com> wrote:
>> >
>> > On Wed, 2016-08-31 at 13:24 -0700, Matt Ranostay wrote:
>> > >
>> > > On Wed, Aug 31, 2016 at 1:18 PM, Pandruvada, Srinivas
>> > > <srinivas.pandruvada@...el.com> wrote:
>> > > >
>> > > >
>> > > > On Tue, 2016-08-30 at 17:41 -0700, Matt Ranostay wrote:
>> > > > >
>> > > > >
>> > > > > On Tue, Aug 30, 2016 at 3:42 PM, Pandruvada, Srinivas
>> > > > > <srinivas.pandruvada@...el.com> wrote:
>> > > > > >
>> > > > > >
>> > > > > >
>> > > > > > Hi All,
>> > > > > >
>> > > > > > I observed that using iio-sensor-proxy.service, the auto
>> > > > > > screen
>> > > > > > rotation flipped on my laptop (Normal -> vertical,
>> > > > > > vertical-
>> > > > > > >
>> > > > > > >
>> > > > > > > normal)
>> > > > > > using kernel v4.8.
>> > > > > >
>> > > > > > Anyone else has seen this?
>> > > > > >
>> > > > > > I did a bisect and found a commit, which I am not sure how
>> > > > > > can
>> > > > > > it
>> > > > > > impact.
>> > > > > Could you post the results of CONFIG_TEST_HASH enabled?
>> > > > Attached dmesg.txt with the CONFIG_TEST_HASH=y.
>> > > >
>> > > > I see
>> > > > [    4.276138] test_hash: __hash_32() has no arch
>> > > > implementation to
>> > > > test.
>> > > > [    4.276138] test_hash: hash_32() has no arch implementation
>> > > > to
>> > > > test.
>> > > > [    4.276139] test_hash: hash_64() has no arch implementation
>> > > > to
>> > > > test.
>> > > > [    4.276141] test_hash: 33152 tests passed.
>> > > >
>> > > Ok have you tested with that patchset reverted? And if so does
>> > > the
>> > > regression disappear?
>> > Yes, but not after adding CONFIG_TEST_HASH=y.
>> > regression disappears.
>> >
>> > >
>> > > I would highly doubt if it was a issue with that dcache patchsets
>> > > it
>> > > wouldn't be breaking a ton of things.
>> > I also think that.
>> Only thing I could suspect is a toolchain bug.. Have crazy idea for
>> you to try below..
>>
>> From the patchset notice the return doesn't cast the result to
>> (unsigned int) as before. But __hash_32_generic is "static inline
>> u32", and maybe the end_name_hash is returning the whole result as a
>> 64-bit unsigned long rather than 32-bit unsigned int.
>>
>> ....
>> static inline unsigned long end_name_hash(unsigned long hash)
>> {
>> - return (unsigned int)hash;
>> + return __hash_32((unsigned int)hash);
>> }
>> ....
>>
>> Just a theory.. Could totally be wrong :).
>>
> I casted to unsigned int, still result is same. I need to look at the
> user space program and compare data it is reading.

Which sensor or sensorhub are you using?   Any chance the data being
read isn't cachealigned?

Thanks,

Matt

>
> Thanks,
> Srinivas
>> >
>> >
>> > Thanks,
>> > Srinivas
>> >
>> > >
>> > >
>> > > >
>> > > >
>> > > > Thanks,
>> > > > Srinivas
>> > > > >
>> > > > >
>> > > > >
>> > > > > Thanks,
>> > > > >
>> > > > > Matt
>> > > > >
>> > > > > >
>> > > > > >
>> > > > > >
>> > > > > >
>> > > > > >
>> > > > > > commit 703b5faf22fbddf984a361e6555f3a03fdba63d9
>> > > > > > Author: George Spelvin <linux@...encehorizons.net>
>> > > > > > Date:   Fri Jun 10 00:22:12 2016 -0400
>> > > > > >
>> > > > > >     fs/dcache.c: Save one 32-bit multiply in dcache lookup
>> > > > > >
>> > > > > >     Noe that we're mixing in the parent pointer earlier, we
>> > > > > >     don't need to use hash_32() to mix its bits.  Instead,
>> > > > > > we
>> > > > > > can
>> > > > > >     just take the msbits of the hash value directly.
>> > > > > >
>> > > > > >     For those applications which use the
>> > > > > > partial_name_hash(),
>> > > > > >     move the multiply to end_name_hash.
>> > > > > >
>> > > > > >     Signed-off-by: George Spelvin <linux@...encehorizons.ne
>> > > > > > t>
>> > > > > >     Signed-off-by: Linus Torvalds <torvalds@...ux-foundatio
>> > > > > > n.or
>> > > > > > g>
>> > > > > >
>> > > > > >
>> > > > > > Thanks,
>> > > > > > Srinivas