Thread (10 messages) 10 messages, 3 authors, 2015-04-29

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

From: Suman Tripathi <hidden>
Date: 2015-04-28 16:53:47
Also in: linux-devicetree, linux-mmc

Possibly related (same subject, not in this thread)

On Monday 27 April 2015 21:25:20 Suman Tripathi wrote:
quoted
On Monday 27 April 2015 20:33:25 Suman Tripathi wrote:
quoted
quoted
On Tuesday 21 April 2015 21:12:39 Suman Tripathi wrote:
quoted
+                       host->quirks |= SDHCI_QUIRK_BROKEN_DMA;
+
+               if (of_get_property(np, "no-cmd23", NULL))
+                       host->quirks2 |=
SDHCI_QUIRK2_HOST_NO_CMD23;
quoted
quoted
quoted
quoted
                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.
quoted
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.

Ok .  sorry for that ..
quoted
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.
quoted
quoted
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?
Yes
This sounds
like version specific quirks, so they are probably present in each
SoC that uses the same version.
Not sure.

On Tue, Apr 28, 2015 at 1:19 AM, Arnd Bergmann [off-list ref] wrote:
On Monday 27 April 2015 21:25:20 Suman Tripathi wrote:
quoted
quoted
On Monday 27 April 2015 20:33:25 Suman Tripathi wrote:
quoted
quoted
On Tuesday 21 April 2015 21:12:39 Suman Tripathi wrote:
quoted
+                       host->quirks |= SDHCI_QUIRK_BROKEN_DMA;
+
+               if (of_get_property(np, "no-cmd23", NULL))
+                       host->quirks2 |=
SDHCI_QUIRK2_HOST_NO_CMD23;
quoted
quoted
quoted
quoted
quoted
                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.
quoted
quoted
quoted
quoted
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.
quoted
quoted
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.
quoted
quoted
quoted
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.
quoted
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?
quoted
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


-- 
Thanks,
with regards,
Suman Tripathi
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