Backport of spi-fsl-spi bugfix to 3.14.y

Please consider commit 4302a59629f7a0bd70fd1605d2b558597517372a (spi: fsl: Fix problem with multi message transfers) for inclusion in stable kernel 3.14.

It fixes a regression when using mmc_spi driver on top of spi-fsl-spi driver (tested with powerpc mpc8313 based board).

Quoted 6 lines · Esben Haabendal

Please consider commit 4302a59629f7a0bd70fd1605d2b558597517372a (spi: fsl: Fix problem with multi message transfers) for inclusion in stable kernel 3.14.

It fixes a regression when using mmc_spi driver on top of spi-fsl-spi driver (tested with powerpc mpc8313 based board).

Has this ever worked?

Quoted 6 lines · Mark Brown

Quoted 6 lines

Please consider commit 4302a59629f7a0bd70fd1605d2b558597517372a (spi: fsl: Fix problem with multi message transfers) for inclusion in stable kernel 3.14.

It fixes a regression when using mmc_spi driver on top of spi-fsl-spi driver (tested with powerpc mpc8313 based board).

Quoted 1 line

Has this ever worked?

Yes, I have used mmc_spi with spi-fsl-spi on the same board with success with in 2.6.33, 3.0 and 3.4.

I have no idea what has caused this to break. Maybe mmc_spi driver was not doing multi message transfers earlier?

Quoted 13 lines · Esben Haabendal

Quoted 8 lines · Mark Brown

Quoted 6 lines

Please consider commit 4302a59629f7a0bd70fd1605d2b558597517372a (spi: fsl: Fix problem with multi message transfers) for inclusion in stable kernel 3.14.

It fixes a regression when using mmc_spi driver on top of spi-fsl-spi driver (tested with powerpc mpc8313 based board).

Has this ever worked?

Yes, I have used mmc_spi with spi-fsl-spi on the same board with success with in 2.6.33, 3.0 and 3.4.

Quoted 2 lines

I have no idea what has caused this to break. Maybe mmc_spi driver was not doing multi message transfers earlier?

So, I now see this has actually been merged into stable without getting to the bottom of why it's helping anything... this is a bit worrying since it's adding new functionality and not really a bug fix. It'd have been good to at least get a followup here.

Quoted 4 lines · Mark Brown

So, I now see this has actually been merged into stable without getting to the bottom of why it's helping anything... this is a bit worrying since it's adding new functionality and not really a bug fix. It'd have been good to at least get a followup here.

Do you want me to revert something from the stable tree? If so, has it also been reverted upstream?

Quoted 9 lines · Greg Kroah-Hartman

Quoted 4 lines · Mark Brown

So, I now see this has actually been merged into stable without getting to the bottom of why it's helping anything... this is a bit worrying since it's adding new functionality and not really a bug fix. It'd have been good to at least get a followup here.

Do you want me to revert something from the stable tree? If so, has it also been reverted upstream?

The patch just isn't an obvious -stable patch - it's adding new functionality, not fixing a bug, and I was surprised to discover it had been added as a result. It's fine as new functionality and therefore hasn't been reverted upstream.

We can probably leave it there, though if this is OK that's a bit of a change, but if this new functionality is a good fix then we're probably leaving other systems unfixed which isn't good, I would be very much happier if we understood what had changed here. If new functionality is OK there's a probably a bunch of other changes we should be pulling back.

Quoted 16 lines · Mark Brown

Quoted 9 lines · Greg Kroah-Hartman

Quoted 4 lines · Mark Brown

So, I now see this has actually been merged into stable without getting to the bottom of why it's helping anything... this is a bit worrying since it's adding new functionality and not really a bug fix. It'd have been good to at least get a followup here.

Do you want me to revert something from the stable tree? If so, has it also been reverted upstream?

The patch just isn't an obvious -stable patch - it's adding new functionality, not fixing a bug, and I was surprised to discover it had been added as a result. It's fine as new functionality and therefore hasn't been reverted upstream.

Quoted 6 lines

We can probably leave it there, though if this is OK that's a bit of a change, but if this new functionality is a good fix then we're probably leaving other systems unfixed which isn't good, I would be very much happier if we understood what had changed here. If new functionality is OK there's a probably a bunch of other changes we should be pulling back.

New functionality shouldn't be added, but sometimes things slip in due to the volume of patches and how people word-smith changelog entries :(

I suspect that the regression I have observed is caused by the combination of the following two commits:

commit 059b8ffeee5b427949872bb6ed5db5ae0788054e
spi: make sure all transfer has proper speed set

commit e6811d1d7a6a38ee637fe219c3b67dbfe17e8b3f
spi: make sure all transfer has bits_per_word set

And the broken behaviour of the spi-fsl-spi driver prior to the (now backported) commit 4302a59629f7a0bd70fd1605d2b558597517372a.

A side effect of the two above mentioned commits is that the spi all transfers (in multi message transfers) have their transfer speed_hz and bits_per_word set, which is not handled properly by spi-fsl-spi.