[PATCH v2 RESEND 2/2] mmc: host: Add some quirks to be read from fdt in sdhci-pltm.c

[PATCH v2 RESEND 2/2] mmc: host: Add some quirks to be read from fdt in sdhci-pltm.c

[Arnd Bergmann]

On Tuesday 21 April 2015 21:12:39 Suman Tripathi wrote:
> index bef250e..9f6a4b9 100644
> --- a/drivers/mmc/host/sdhci-pltfm.c
> +++ b/drivers/mmc/host/sdhci-pltfm.c
> @@ -85,6 +85,21 @@ void sdhci_get_of_property(struct platform_device *pdev)
>  
>                 if (of_get_property(np, "broken-cd", NULL))
>                         host->quirks |= SDHCI_QUIRK_BROKEN_CARD_DETECTION;
> +               
> +               if (of_get_property(np, "delay-after-power", NULL))
> +                       host->quirks |= SDHCI_QUIRK_DELAY_AFTER_POWER;
> +
> +               if (of_get_property(np, "no-hispd", NULL))
> +                       host->quirks |= SDHCI_QUIRK_NO_HISPD_BIT;
> +
> +               if (of_get_property(np, "broken-adma", NULL))
> +                       host->quirks |= SDHCI_QUIRK_BROKEN_ADMA;
> +               
> +               if (of_get_property(np, "broken-dma", NULL))
> +                       host->quirks |= SDHCI_QUIRK_BROKEN_DMA;
> +
> +               if (of_get_property(np, "no-cmd23", NULL))
> +                       host->quirks2 |= SDHCI_QUIRK2_HOST_NO_CMD23;
>  
>                 if (of_get_property(np, "no-1-8-v", NULL))
>                         host->quirks2 |= SDHCI_QUIRK2_NO_1_8_V;
> 

Any property you add needs to be documented in the DT binding.

If possible, add generic properties for each bug you have mmc.txt
rather than the driver specific sdhci.txt, and implement the
parsing in a common function that is used for all mmc hosts.

An alternative would be to set all these bits based on the compatible
string of your host, if that is the only one that has all these bugs.

	Arnd

[PATCH v2 RESEND 2/2] mmc: host: Add some quirks to be read from fdt in sdhci-pltm.c

[Suman Tripathi]

On Tuesday 21 April 2015 21:12:39 Suman Tripathi wrote:
> index bef250e..9f6a4b9 100644
> --- a/drivers/mmc/host/sdhci-pltfm.c
> +++ b/drivers/mmc/host/sdhci-pltfm.c
> @@ -85,6 +85,21 @@ void sdhci_get_of_property(struct platform_device *pdev)
>
>                 if (of_get_property(np, "broken-cd", NULL))
>                         host->quirks |= SDHCI_QUIRK_BROKEN_CARD_DETECTION;
> +
> +               if (of_get_property(np, "delay-after-power", NULL))
> +                       host->quirks |= SDHCI_QUIRK_DELAY_AFTER_POWER;
> +
> +               if (of_get_property(np, "no-hispd", NULL))
> +                       host->quirks |= SDHCI_QUIRK_NO_HISPD_BIT;
> +
> +               if (of_get_property(np, "broken-adma", NULL))
> +                       host->quirks |= SDHCI_QUIRK_BROKEN_ADMA;
> +
> +               if (of_get_property(np, "broken-dma", NULL))
> +                       host->quirks |= SDHCI_QUIRK_BROKEN_DMA;
> +
> +               if (of_get_property(np, "no-cmd23", NULL))
> +                       host->quirks2 |= SDHCI_QUIRK2_HOST_NO_CMD23;
>
>                 if (of_get_property(np, "no-1-8-v", NULL))
>                         host->quirks2 |= SDHCI_QUIRK2_NO_1_8_V;
>

Any property you add needs to be documented in the DT binding.

If possible, add generic properties for each bug you have mmc.txt
rather than the driver specific sdhci.txt, and implement the
I will add the binding in mmc.txt. I thought this was present but not.

parsing in a common function that is used for all mmc hosts.
As per mine understanding the sdhci_get_of_porperty is a common
parsing function  . Am I wrong ??

An alternative would be to set all these bits based on the compatible
string of your host, if that is the only one that has all these bugs.

The host driver  (arasan) is reused but this quirks are needed due to
board issues. so I have a control over dtb only to fix this.

On Tue, Apr 21, 2015 at 9:16 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> On Tuesday 21 April 2015 21:12:39 Suman Tripathi wrote:
>> index bef250e..9f6a4b9 100644
>> --- a/drivers/mmc/host/sdhci-pltfm.c
>> +++ b/drivers/mmc/host/sdhci-pltfm.c
>> @@ -85,6 +85,21 @@ void sdhci_get_of_property(struct platform_device *pdev)
>>
>>                 if (of_get_property(np, "broken-cd", NULL))
>>                         host->quirks |= SDHCI_QUIRK_BROKEN_CARD_DETECTION;
>> +
>> +               if (of_get_property(np, "delay-after-power", NULL))
>> +                       host->quirks |= SDHCI_QUIRK_DELAY_AFTER_POWER;
>> +
>> +               if (of_get_property(np, "no-hispd", NULL))
>> +                       host->quirks |= SDHCI_QUIRK_NO_HISPD_BIT;
>> +
>> +               if (of_get_property(np, "broken-adma", NULL))
>> +                       host->quirks |= SDHCI_QUIRK_BROKEN_ADMA;
>> +
>> +               if (of_get_property(np, "broken-dma", NULL))
>> +                       host->quirks |= SDHCI_QUIRK_BROKEN_DMA;
>> +
>> +               if (of_get_property(np, "no-cmd23", NULL))
>> +                       host->quirks2 |= SDHCI_QUIRK2_HOST_NO_CMD23;
>>
>>                 if (of_get_property(np, "no-1-8-v", NULL))
>>                         host->quirks2 |= SDHCI_QUIRK2_NO_1_8_V;
>>
>
> Any property you add needs to be documented in the DT binding.
>
> If possible, add generic properties for each bug you have mmc.txt
> rather than the driver specific sdhci.txt, and implement the
> parsing in a common function that is used for all mmc hosts.
>
> An alternative would be to set all these bits based on the compatible
> string of your host, if that is the only one that has all these bugs.
>
>         Arnd



-- 
Thanks,
with regards,
Suman Tripathi

[PATCH v2 RESEND 2/2] mmc: host: Add some quirks to be read from fdt in sdhci-pltm.c

[Arnd Bergmann]

On Monday 27 April 2015 20:33:25 Suman Tripathi wrote:
> > On Tuesday 21 April 2015 21:12:39 Suman Tripathi wrote:
> > > index bef250e..9f6a4b9 100644
> > > --- a/drivers/mmc/host/sdhci-pltfm.c
> > > +++ b/drivers/mmc/host/sdhci-pltfm.c
> > > @@ -85,6 +85,21 @@ void sdhci_get_of_property(struct platform_device
> > > *pdev)
> > >
> > >                 if (of_get_property(np, "broken-cd", NULL))
> > >                         host->quirks |=
> > >SDHCI_QUIRK_BROKEN_CARD_DETECTION;
> > >
> > > +
> > > +               if (of_get_property(np, "delay-after-power", NULL))
> > > +                       host->quirks |= SDHCI_QUIRK_DELAY_AFTER_POWER;
> > > +
> > > +               if (of_get_property(np, "no-hispd", NULL))
> > > +                       host->quirks |= SDHCI_QUIRK_NO_HISPD_BIT;
> > > +
> > > +               if (of_get_property(np, "broken-adma", NULL))
> > > +                       host->quirks |= SDHCI_QUIRK_BROKEN_ADMA;
> > > +
> > > +               if (of_get_property(np, "broken-dma", NULL))
> > > +                       host->quirks |= SDHCI_QUIRK_BROKEN_DMA;
> > > +
> > > +               if (of_get_property(np, "no-cmd23", NULL))
> > > +                       host->quirks2 |= SDHCI_QUIRK2_HOST_NO_CMD23;
> > >
> > >                 if (of_get_property(np, "no-1-8-v", NULL))
> > >                         host->quirks2 |= SDHCI_QUIRK2_NO_1_8_V;
> > 
> > Any property you add needs to be documented in the DT binding.
> > If possible, add generic properties for each bug you have mmc.txt
> > rather than the driver specific sdhci.txt, and implement the
> I will add the binding in mmc.txt. I thought this was present but not.
> 
> > parsing in a common function that is used for all mmc hosts.
> As per mine understanding the sdhci_get_of_porperty is a common
> parsing function  . Am I wrong ??

No, this is only used for sdhci, not for the other controllers.

> > An alternative would be to set all these bits based on the compatible
> > string of your host, if that is the only one that has all these bugs.
> 
> The host driver  (arasan) is reused but this quirks are needed due to
> board issues. so I have a control over dtb only to fix this.

What is the nature of the bug on that board? Is there a different
way to describe that without introducing six new properties?

	Arnd

[PATCH v2 RESEND 2/2] mmc: host: Add some quirks to be read from fdt in sdhci-pltm.c

[Suman Tripathi]

On Monday 27 April 2015 20:33:25 Suman Tripathi wrote:
> > On Tuesday 21 April 2015 21:12:39 Suman Tripathi wrote:
> > > index bef250e..9f6a4b9 100644
> > > --- a/drivers/mmc/host/sdhci-pltfm.c
> > > +++ b/drivers/mmc/host/sdhci-pltfm.c
> > > @@ -85,6 +85,21 @@ void sdhci_get_of_property(struct platform_device
> > > *pdev)
> > >
> > >                 if (of_get_property(np, "broken-cd", NULL))
> > >                         host->quirks |=
> > >SDHCI_QUIRK_BROKEN_CARD_DETECTION;
> > >
> > > +
> > > +               if (of_get_property(np, "delay-after-power", NULL))
> > > +                       host->quirks |= SDHCI_QUIRK_DELAY_AFTER_POWER;
> > > +
> > > +               if (of_get_property(np, "no-hispd", NULL))
> > > +                       host->quirks |= SDHCI_QUIRK_NO_HISPD_BIT;
> > > +
> > > +               if (of_get_property(np, "broken-adma", NULL))
> > > +                       host->quirks |= SDHCI_QUIRK_BROKEN_ADMA;
> > > +
> > > +               if (of_get_property(np, "broken-dma", NULL))
> > > +                       host->quirks |= SDHCI_QUIRK_BROKEN_DMA;
> > > +
> > > +               if (of_get_property(np, "no-cmd23", NULL))
> > > +                       host->quirks2 |= SDHCI_QUIRK2_HOST_NO_CMD23;
> > >
> > >                 if (of_get_property(np, "no-1-8-v", NULL))
> > >                         host->quirks2 |= SDHCI_QUIRK2_NO_1_8_V;
> >
> > Any property you add needs to be documented in the DT binding.
> > If possible, add generic properties for each bug you have mmc.txt
> > rather than the driver specific sdhci.txt, and implement the
> I will add the binding in mmc.txt. I thought this was present but not.
>
> > parsing in a common function that is used for all mmc hosts.
> As per mine understanding the sdhci_get_of_porperty is a common
> parsing function  . Am I wrong ??

No, this is only used for sdhci, not for the other controllers.

But our's is a SHCI variant so I added it in this file.

> > An alternative would be to set all these bits based on the compatible
> > string of your host, if that is the only one that has all these bugs.
>
> The host driver  (arasan) is reused but this quirks are needed due to
> board issues. so I have a control over dtb only to fix this.

What is the nature of the bug on that board? Is there a different
way to describe that without introducing six new properties?

Sorry it is board and IP as well SoC errata's,

1. Delay after power is required due to some voltage issues that will
be fixed in next board revision

2. We need to support PIO mode as of now because DMA or ADMA requires
some kind of translation driver that I am working on.

3. The version of arasan variant we have in our SoC doesn't have the
HISPD  bit field in HI-SPEED SD card. So this makes HI-SPEED sdcard
work.

4. NO_CMD23 is required for eMMC cards.

These are not new properties.  Only the fact is I am using it for our
SoC from dtb. These quirks are already there in mmc common framework.
Nothing is new.





On Mon, Apr 27, 2015 at 8:55 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> On Monday 27 April 2015 20:33:25 Suman Tripathi wrote:
>> > On Tuesday 21 April 2015 21:12:39 Suman Tripathi wrote:
>> > > index bef250e..9f6a4b9 100644
>> > > --- a/drivers/mmc/host/sdhci-pltfm.c
>> > > +++ b/drivers/mmc/host/sdhci-pltfm.c
>> > > @@ -85,6 +85,21 @@ void sdhci_get_of_property(struct platform_device
>> > > *pdev)
>> > >
>> > >                 if (of_get_property(np, "broken-cd", NULL))
>> > >                         host->quirks |=
>> > >SDHCI_QUIRK_BROKEN_CARD_DETECTION;
>> > >
>> > > +
>> > > +               if (of_get_property(np, "delay-after-power", NULL))
>> > > +                       host->quirks |= SDHCI_QUIRK_DELAY_AFTER_POWER;
>> > > +
>> > > +               if (of_get_property(np, "no-hispd", NULL))
>> > > +                       host->quirks |= SDHCI_QUIRK_NO_HISPD_BIT;
>> > > +
>> > > +               if (of_get_property(np, "broken-adma", NULL))
>> > > +                       host->quirks |= SDHCI_QUIRK_BROKEN_ADMA;
>> > > +
>> > > +               if (of_get_property(np, "broken-dma", NULL))
>> > > +                       host->quirks |= SDHCI_QUIRK_BROKEN_DMA;
>> > > +
>> > > +               if (of_get_property(np, "no-cmd23", NULL))
>> > > +                       host->quirks2 |= SDHCI_QUIRK2_HOST_NO_CMD23;
>> > >
>> > >                 if (of_get_property(np, "no-1-8-v", NULL))
>> > >                         host->quirks2 |= SDHCI_QUIRK2_NO_1_8_V;
>> >
>> > Any property you add needs to be documented in the DT binding.
>> > If possible, add generic properties for each bug you have mmc.txt
>> > rather than the driver specific sdhci.txt, and implement the
>> I will add the binding in mmc.txt. I thought this was present but not.
>>
>> > parsing in a common function that is used for all mmc hosts.
>> As per mine understanding the sdhci_get_of_porperty is a common
>> parsing function  . Am I wrong ??
>
> No, this is only used for sdhci, not for the other controllers.
>
>> > An alternative would be to set all these bits based on the compatible
>> > string of your host, if that is the only one that has all these bugs.
>>
>> The host driver  (arasan) is reused but this quirks are needed due to
>> board issues. so I have a control over dtb only to fix this.
>
> What is the nature of the bug on that board? Is there a different
> way to describe that without introducing six new properties?
>
>         Arnd



-- 
Thanks,
with regards,
Suman Tripathi

[PATCH v2 RESEND 2/2] mmc: host: Add some quirks to be read from fdt in sdhci-pltm.c

[Arnd Bergmann]

On Monday 27 April 2015 21:25:20 Suman Tripathi wrote:
> > On Monday 27 April 2015 20:33:25 Suman Tripathi wrote:
> > > > On Tuesday 21 April 2015 21:12:39 Suman Tripathi wrote:
> > > > > +                       host->quirks |= SDHCI_QUIRK_BROKEN_DMA;
> > > > > +
> > > > > +               if (of_get_property(np, "no-cmd23", NULL))
> > > > > +                       host->quirks2 |= SDHCI_QUIRK2_HOST_NO_CMD23;
> > > > > 
> > > > >                 if (of_get_property(np, "no-1-8-v", NULL))
> > > > >                 
> > > > >                         host->quirks2 |= SDHCI_QUIRK2_NO_1_8_V;
> > > > 
> > > > Any property you add needs to be documented in the DT binding.
> > > > If possible, add generic properties for each bug you have mmc.txt
> > > > rather than the driver specific sdhci.txt, and implement the
> > > 
> > > I will add the binding in mmc.txt. I thought this was present but not.
> > > 
> > > > parsing in a common function that is used for all mmc hosts.
> > > 
> > > As per mine understanding the sdhci_get_of_porperty is a common
> > > parsing function  . Am I wrong ??
> 

A small side note: please fix your email client to use proper attribution
of the citations. The way you reply, nobody knows what you are saying
compare to what you quote. Also, reduce the quotation to the parts you
are replying to.

> > No, this is only used for sdhci, not for the other controllers.
> 
> But our's is a SHCI variant so I added it in this file.

That's my point: a lot of the bugs are independent of the specific
host controller and could happen with any one of them. We want to
ensure that nobody tries to add another property with similar
semantics and a different name just because they are using a
different driver.
 
> > > An alternative would be to set all these bits based on the compatible
> > > string of your host, if that is the only one that has all these bugs.
> >
> > The host driver  (arasan) is reused but this quirks are needed due to
> > board issues. so I have a control over dtb only to fix this.
> 
> What is the nature of the bug on that board? Is there a different
> way to describe that without introducing six new properties?
> 
> Sorry it is board and IP as well SoC errata's,
> 
> 1. Delay after power is required due to some voltage issues that will
> be fixed in next board revision

This is clearly not sdhci-specific, so make that a generic property
for all mmc.

> 2. We need to support PIO mode as of now because DMA or ADMA requires
> some kind of translation driver that I am working on.

But this does not describe the hardware properties. Don't add properties
that describe the lack of a kernel driver. If you can't do DMA yet,
use a dma-ranges property that lists one empty range to prevent
dma_set_mask() from working, so it will fall back to PIO mode. You
may have to fix the driver if that doesn't already work.

What kind of driver do you need here?

> 3. The version of arasan variant we have in our SoC doesn't have the
> HISPD  bit field in HI-SPEED SD card. So this makes HI-SPEED sdcard
> work.
> 
> 4. NO_CMD23 is required for eMMC cards.
> 
> These are not new properties.  Only the fact is I am using it for our
> SoC from dtb. These quirks are already there in mmc common framework.
> Nothing is new.

Are you sure that you have version 8.9a of the Arasan SDHCI? This sounds
like version specific quirks, so they are probably present in each
SoC that uses the same version.

	Arnd

[PATCH v2 RESEND 2/2] mmc: host: Add some quirks to be read from fdt in sdhci-pltm.c

[Suman Tripathi]

Hi Arnd,

Please ignore the previous reply.

On Tue, Apr 28, 2015 at 1:19 AM, Arnd Bergmann <arnd@arndb.de> wrote:
> On Monday 27 April 2015 21:25:20 Suman Tripathi wrote:
>> > On Monday 27 April 2015 20:33:25 Suman Tripathi wrote:
>> > > > On Tuesday 21 April 2015 21:12:39 Suman Tripathi wrote:
>> > > > > +                       host->quirks |= SDHCI_QUIRK_BROKEN_DMA;
>> > > > > +
>> > > > > +               if (of_get_property(np, "no-cmd23", NULL))
>> > > > > +                       host->quirks2 |= SDHCI_QUIRK2_HOST_NO_CMD23;
>> > > > >
>> > > > >                 if (of_get_property(np, "no-1-8-v", NULL))
>> > > > >
>> > > > >                         host->quirks2 |= SDHCI_QUIRK2_NO_1_8_V;
>> > > >
>> > > > Any property you add needs to be documented in the DT binding.
>> > > > If possible, add generic properties for each bug you have mmc.txt
>> > > > rather than the driver specific sdhci.txt, and implement the
>> > >
>> > > I will add the binding in mmc.txt. I thought this was present but not.
>> > >
>> > > > parsing in a common function that is used for all mmc hosts.
>> > >
>> > > As per mine understanding the sdhci_get_of_porperty is a common
>> > > parsing function  . Am I wrong ??
>>
>
> A small side note: please fix your email client to use proper attribution
> of the citations. The way you reply, nobody knows what you are saying
> compare to what you quote. Also, reduce the quotation to the parts you
> are replying to.
>

Okay. Sorry for that. I fixed it.

>> > No, this is only used for sdhci, not for the other controllers.
>>
>> But our's is a SHCI variant so I added it in this file.
>
> That's my point: a lot of the bugs are independent of the specific
> host controller and could happen with any one of them. We want to
> ensure that nobody tries to add another property with similar
> semantics and a different name just because they are using a
> different driver.

Then I am not finding a reason why we have sdhci_get_of_property function ?? .
 I added a generic names like broken-adma that everyone can reuse it.
I made mistake of not adding it in the binding.

For eg : broken-cd is not added by me but I can use it. So I added
something like broken-adma as it was not present.

>
>> > > An alternative would be to set all these bits based on the compatible
>> > > string of your host, if that is the only one that has all these bugs.
>> >
>> > The host driver  (arasan) is reused but this quirks are needed due to
>> > board issues. so I have a control over dtb only to fix this.
>>
>> What is the nature of the bug on that board? Is there a different
>> way to describe that without introducing six new properties?
>>
>> Sorry it is board and IP as well SoC errata's,
>>
>> 1. Delay after power is required due to some voltage issues that will
>> be fixed in next board revision
>
> This is clearly not sdhci-specific, so make that a generic property
> for all mmc.
>

Okay

>> 2. We need to support PIO mode as of now because DMA or ADMA requires
>> some kind of translation driver that I am working on.
>
> But this does not describe the hardware properties. Don't add properties
> that describe the lack of a kernel driver. If you can't do DMA yet,
> use a dma-ranges property that lists one empty range to prevent
> dma_set_mask() from working, so it will fall back to PIO mode. You
> may have to fix the driver if that doesn't already work.
>

The generic sdhc framework doesn't have this capabiltiy. It uses the
quirks to identify the broken DMA and ADMA modes even
if the controller is capable of.

> What kind of driver do you need here?

For DMA and adma we need some 32 bit to 64 bit translation driver.
The existing arasan driver only support 32 bit.

>
>> 3. The version of arasan variant we have in our SoC doesn't have the
>> HISPD  bit field in HI-SPEED SD card. So this makes HI-SPEED sdcard
>> work.
>>
>> 4. NO_CMD23 is required for eMMC cards.
>>
>> These are not new properties.  Only the fact is I am using it for our
>> SoC from dtb. These quirks are already there in mmc common framework.
>> Nothing is new.
>
> Are you sure that you have version 8.9a of the Arasan SDHCI? This sounds

No We are using 4.9a ARASAN SDHCI

> like version specific quirks, so they are probably present in each
> SoC that uses the same version.

Not sure

>
>         Arnd



-- 
Thanks,
with regards,
Suman Tripathi

[PATCH v2 RESEND 2/2] mmc: host: Add some quirks to be read from fdt in sdhci-pltm.c

[Arnd Bergmann]

On Wednesday 29 April 2015 12:34:41 Suman Tripathi wrote:
> On Tue, Apr 28, 2015 at 1:19 AM, Arnd Bergmann <arnd@arndb.de> wrote:
> > On Monday 27 April 2015 21:25:20 Suman Tripathi wrote:
> >> > On Monday 27 April 2015 20:33:25 Suman Tripathi wrote:
> >> > > > On Tuesday 21 April 2015 21:12:39 Suman Tripathi wrote:
> >> > > > > +                       host->quirks |= SDHCI_QUIRK_BROKEN_DMA;
> >> > > > > +
> >> > > > > +               if (of_get_property(np, "no-cmd23", NULL))
> >> > > > > +                       host->quirks2 |= SDHCI_QUIRK2_HOST_NO_CMD23;
> >> > > > >
> >> > > > >                 if (of_get_property(np, "no-1-8-v", NULL))
> >> > > > >
> >> > > > >                         host->quirks2 |= SDHCI_QUIRK2_NO_1_8_V;
> >> > > >
> >> > > > Any property you add needs to be documented in the DT binding.
> >> > > > If possible, add generic properties for each bug you have mmc.txt
> >> > > > rather than the driver specific sdhci.txt, and implement the
> >> > >
> >> > > I will add the binding in mmc.txt. I thought this was present but not.
> >> > >
> >> > > > parsing in a common function that is used for all mmc hosts.
> >> > >
> >> > > As per mine understanding the sdhci_get_of_porperty is a common
> >> > > parsing function  . Am I wrong ??
> >>
> >
> > A small side note: please fix your email client to use proper attribution
> > of the citations. The way you reply, nobody knows what you are saying
> > compare to what you quote. Also, reduce the quotation to the parts you
> > are replying to.
> >
> 
> Okay. Sorry for that. I fixed it.

Ok, much better.

> >> > No, this is only used for sdhci, not for the other controllers.
> >>
> >> But our's is a SHCI variant so I added it in this file.
> >
> > That's my point: a lot of the bugs are independent of the specific
> > host controller and could happen with any one of them. We want to
> > ensure that nobody tries to add another property with similar
> > semantics and a different name just because they are using a
> > different driver.
> 
> Then I am not finding a reason why we have sdhci_get_of_property function ?? .
>  I added a generic names like broken-adma that everyone can reuse it.
> I made mistake of not adding it in the binding.
> 
> For eg : broken-cd is not added by me but I can use it. So I added
> something like broken-adma as it was not present.

The common mmc_of_parse() handles "broken-cd", and the sdhci_get_of_property()
does so too. This is really a mistake we made earlier when it was added
to sdhi instead of the common code. We should remove the parsing for
that property from the sdhci driver and have the core handle it always,
but that require someone to do it and ensure that no subtle ABI changes
are introduced on the way.

For new properties, the right way is to add it to the common function only.

> >> 2. We need to support PIO mode as of now because DMA or ADMA requires
> >> some kind of translation driver that I am working on.
> >
> > But this does not describe the hardware properties. Don't add properties
> > that describe the lack of a kernel driver. If you can't do DMA yet,
> > use a dma-ranges property that lists one empty range to prevent
> > dma_set_mask() from working, so it will fall back to PIO mode. You
> > may have to fix the driver if that doesn't already work.
> >
> 
> The generic sdhc framework doesn't have this capabiltiy. It uses the
> quirks to identify the broken DMA and ADMA modes even
> if the controller is capable of.
> 
> > What kind of driver do you need here?
> 
> For DMA and adma we need some 32 bit to 64 bit translation driver.
> The existing arasan driver only support 32 bit.

Ok, that sounds like a very simple case: The width of the DMA is determined
from DT by looking at the dma-ranges properties. If it doesn't work, one
of these steps that are supposed to happen are broken and you should
try to find out which one that is and fix it:

- The parent node of the sdhci device in DT must not claim to support
  64 bit if the bus is only 32-bit wide. A dma-ranges property containing
  "<0 0 1 0>" would describe a bus that has a 32-bit DMA address range that
  is 1:1 mapped to the root bus, which is the default.

- The ARM64 code must check that property in a call to dma_set_mask()
  or dma_set_mask_and_coherent(), and not allow a mask to be set that
  exceeds the size of the dma-ranges property.

- The sdhci driver must call dma_set_mask() or dma_set_mask_and_coherent()
  with the mask that is claimed by the device (usually 32 bit or 64 bit)
  and check the result.

- If the call to dma_set_mask() for the 64-bit mask fails, the driver must
  fall back to using the 32-bit mask and not attempt to use the 64-bit
  DMA registers.

This is the behavior we require anyway, and if this all works, you don't
need the extra quirks.

The above assumes that the limitation is enforced by the bus (e.g. an
AHB bus can only do 32-bit DMA). It would be a little different if you
have a 64-bit AXI bus and the Arasan device itself is limited to 32-bit
independent of the width of the bus it is connected to. Can you find out
which of these two cases you have?

> >> 3. The version of arasan variant we have in our SoC doesn't have the
> >> HISPD  bit field in HI-SPEED SD card. So this makes HI-SPEED sdcard
> >> work.
> >>
> >> 4. NO_CMD23 is required for eMMC cards.
> >>
> >> These are not new properties.  Only the fact is I am using it for our
> >> SoC from dtb. These quirks are already there in mmc common framework.
> >> Nothing is new.
> >
> > Are you sure that you have version 8.9a of the Arasan SDHCI? This sounds
> 
> No We are using 4.9a ARASAN SDHCI

Ok, then add a compatible string for this version to the arasan binding,
and set the quirks flags only for the 4.9a version and not for the 8.9a
version.

	Arnd

[PATCH v2 RESEND 2/2] mmc: host: Add some quirks to be read from fdt in sdhci-pltm.c

[Arnd Bergmann]

On Wednesday 29 April 2015 19:55:53 Suman Tripathi wrote:
> >
> > The above assumes that the limitation is enforced by the bus (e.g. an
> > AHB bus can only do 32-bit DMA). It would be a little different if you
> > have a 64-bit AXI bus and the Arasan device itself is limited to 32-bit
> > independent of the width of the bus it is connected to. Can you find out
> > which of these two cases you have?
> >
> 
> We have 64 bit AXI and Arasan device or controller is 32 bit . So there is
> 64 bit AXI to 32 bit AHB translation.

Please be very specific here. If this is an AHB based MMC controller, you
should model that AHB bus in DT, with the 32-bit dma-ranges.

However, if this is an AXI based MMC controller that is limited to 32-bit
DMA, the correct change would be to make ensure that the driver never
asks for a 64-bit DMA mask with this hardware.

Both will result in a 32-bit dma mask being used, and high DMA handled
through the block bounce code or swiotlb, but it's best to ensure that
the DT representation matches the actual hardware as closely as possible,
so it keeps working when you change something in a future chip.

	Arnd