Re: [PATCH 2.6.20-rc2] Add a quirk to allow at least some ENE PCI SD card readers to work again

I demand that Pierre Ossman may or may not have written...

Darren Salt wrote:
Add a quirk to allow at least some ENE PCI SD card readers to work again

Support for these devices was broken for 2.6.18-rc1 and later by commit
146ad66eac836c0b976c98f428d73e1f6a75270d, which added voltage level
support.

This restores the previous behaviour for these devices (PCI ID 1524:0550).

Signed-off-by: Darren Salt <linux@xxxxxxxxxxxxxxxxxxxxxxxxxxx>

Oh? If this is the source of problems for ENE controllers then this is
indeed a magnificent find. Good work.

I'd like to know a little more about it though:

- Exactly what errors where you seeing without this patch?

The device was recognised, but insertion of a card was effectively not being
noticed, with no messages in the kernel log. (I say 'effectively': interrupts
were definitely being received and processed.)

- The patch effectively sets only the highest power. Have you tried other
bit combinations to figure out if all of these are really needed?

I have now... bits 4 to 7 are ignored, so 0x0F is fine; and it's what's
needed since lower values don't work.

It turns out that the reader only supports one voltage (caps &
SDHCI_CAN_VDD_330 is true, the others are false) and the code was already
selecting the correct value for the hardware. So I tried reverting the patch
and ensuring that the first writeb() in sdhci_set_power() isn't done if the
second one will be - and things started working properly again.

(This also means that the current patch is broken as the limited voltage
range needs to also be reported to the MMC layer).

- Could you change the patch so that it covers all ENE controllers and send
it out for testing on sdhci-devel? That way we could see if there are any
more ENE controllers that will benefit from this quirk. Just remember to
ask people for a lspci.

Sent as a follow-up to this message.

(BTW, is there a version of Thunderbird which preserves Mail-Followup-To in
followups? I ask because I see that that header got lost...)

--
| Darren Salt | linux or ds at | nr. Ashington, | Toon
| RISC OS, Linux | youmustbejoking,demon,co,uk | Northumberland | Army
| + Generate power using sun, wind, water, nuclear. FORGET COAL AND OIL.

File already exists, 0:1
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