Re: [RFC 0/2] mmc: sdhi: make use of CBSY

Re: [RFC 0/2] mmc: sdhi: make use of CBSY

[Dirk Behme]

Hi,

On 26.01.2016 12:46, Wolfram Sang wrote:
> Honestly, I still think this is a micro-optimization: Assuming SCLKDIVEN is
> basically CBSY plus 8 SD clock cycles, then we'd save in the best case (SD
> clock is slowest, 24 MHz) around 333ns while we are polling with 1 us
> granularity...
>
> However, in case I assumed something wrong and so you guys have something to
> play with, here is an RFC. Let me know what you think.
>
> Wolfram Sang (2):
>   mmc: tmio/sdhi: introduce flag for RCar specific features
>   mmc: sdhi: on RCar, make use of CBSY bit
>
>  drivers/mmc/host/sh_mobile_sdhi.c | 19 +++++++++++++------
>  drivers/mmc/host/tmio_mmc_pio.c   |  6 +++---
>  include/linux/mfd/tmio.h          |  4 ++--
>  include/linux/mmc/tmio.h          |  3 +++
>  4 files changed, 21 insertions(+), 11 deletions(-)


Checking the recent kernel [1] it seems to me that this changes never 
made it into mainline.

Does anybody remember why and/or the history?

Best regards

Dirk

[1] 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/mmc/host/sh_mobile_sdhi.c#n509

Re: [RFC 0/2] mmc: sdhi: make use of CBSY

[Wolfram Sang]

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Hi Dirk,

> Checking the recent kernel [1] it seems to me that this changes never made
> it into mainline.
> 
> Does anybody remember why and/or the history?

As for Ulf, it was RFC, so no urge to pick it up. As for me, I was
waiting for more feedback and then it fell through the cracks.

Thanks for bringing it up again. I am curious, does it make a
difference somewhere despite being closer to the docs?

Have a nice weekend,

   Wolfram


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Re: [RFC 0/2] mmc: sdhi: make use of CBSY

[Dirk Behme]

On 29.04.2017 11:55, Wolfram Sang wrote:
> Hi Dirk,
>
>> Checking the recent kernel [1] it seems to me that this changes never made
>> it into mainline.
>>
>> Does anybody remember why and/or the history?
>
> As for Ulf, it was RFC, so no urge to pick it up. As for me, I was
> waiting for more feedback and then it fell through the cracks.
>
> Thanks for bringing it up again. I am curious, does it make a
> difference somewhere despite being closer to the docs?


No, not that I'm aware atm. Most probably, its only relevant from 
review point of view.

We just found this topic while comparing what was applied to an older 
internal test version compared to recent mainline.

So if it does no harm an makes the code closer to the docs, would it 
be an option to apply it?

Best regards

Dirk

Re: [RFC 0/2] mmc: sdhi: make use of CBSY

[Wolfram Sang]

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> So if it does no harm an makes the code closer to the docs, would it be an
> option to apply it?

We likely need to wait a cycle because of some on-going refactor work,
but in general: yes, I'll pick it up again.


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