From: Wolfgang Muees <[email protected]>
The switch command (typically speed switching from 25 to 50 MHz clock)
can be rejected by _both_ the host controller/driver and by the card.
Elder revisions of the SD card do not support speed switching.
Fail gracefully if the reject is comming from the card.
Signed-off-by: Wolfgang Muees <[email protected]>
---
diff -uprN 2_6_29_rc7_patch_retries/drivers/mmc/core/mmc.c 2_6_29_rc7_patch_switch/drivers/mmc/core/mmc.c
--- 2_6_29_rc7_patch_retries/drivers/mmc/core/mmc.c 2009-03-04 02:05:22.000000000 +0100
+++ 2_6_29_rc7_patch_switch/drivers/mmc/core/mmc.c 2009-06-11 17:09:48.000000000 +0200
@@ -180,11 +180,11 @@ static int mmc_read_ext_csd(struct mmc_c
err = mmc_send_ext_csd(card, ext_csd);
if (err) {
- /*
- * We all hosts that cannot perform the command
- * to fail more gracefully
- */
- if (err != -EINVAL)
+ /* If the host or the card can't do the switch,
+ * fail more gracefully. */
+ if ((err != -EINVAL)
+ && (err != -ENOSYS)
+ && (err != -EFAULT))
goto out;
/*
diff -uprN 2_6_29_rc7_patch_retries/drivers/mmc/core/sd.c 2_6_29_rc7_patch_switch/drivers/mmc/core/sd.c
--- 2_6_29_rc7_patch_retries/drivers/mmc/core/sd.c 2009-04-07 15:39:22.000000000 +0200
+++ 2_6_29_rc7_patch_switch/drivers/mmc/core/sd.c 2009-06-11 17:09:43.000000000 +0200
@@ -210,11 +210,11 @@ static int mmc_read_switch(struct mmc_ca
err = mmc_sd_switch(card, 0, 0, 1, status);
if (err) {
- /*
- * We all hosts that cannot perform the command
- * to fail more gracefully
- */
- if (err != -EINVAL)
+ /* If the host or the card can't do the switch,
+ * fail more gracefully. */
+ if ((err != -EINVAL)
+ && (err != -ENOSYS)
+ && (err != -EFAULT))
goto out;
printk(KERN_WARNING "%s: problem reading switch "
---
regards
i. A. Wolfgang M?es
--
Auerswald GmbH & Co. KG
Hardware Development
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Telefax: +49 (0)5306 9219 94
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?
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On Thu, 11 Jun 2009 16:13:27 +0100
Wolfgang Mües <[email protected]> wrote:
> From: Wolfgang Muees <[email protected]>
>
> The switch command (typically speed switching from 25 to 50 MHz clock)
> can be rejected by _both_ the host controller/driver and by the card.
> Elder revisions of the SD card do not support speed switching.
> Fail gracefully if the reject is comming from the card.
>
> Signed-off-by: Wolfgang Muees <[email protected]>
>
Have you ever seen this in practice? For SD there are several checks
before the switch command is actually issued. Sounds like there is
something else wrong here. Have you turned off your EMP thingy? ;)
PS. Please use the @ossman.eu address.
Rgds
--
-- Pierre Ossman
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Hello Pierre,
Am Samstag, 13. Juni 2009 schrieb Pierre Ossman:
> > The switch command (typically speed switching from 25 to 50 MHz clock)
> > can be rejected by _both_ the host controller/driver and by the card.
> > Elder revisions of the SD card do not support speed switching.
> > Fail gracefully if the reject is comming from the card.
> Have you ever seen this in practice?
Yes, I have. An old 1 GByte SD card.
> For SD there are several checks
> before the switch command is actually issued.
But there are two cases not covered by these checks:
a) the switch command is supported, but the card is not capable of switching
to 50 MHz.
b) the card rejects the switch command in SPI mode, because it is not
mandatory here.
So yes, the checks can be improved. But only extending the error codes was a
simple, fast and minimal solution.
regards
i. A. Wolfgang Mües
--
Auerswald GmbH & Co. KG
Hardware Development
Telefon: +49 (0)5306 9219 0
Telefax: +49 (0)5306 9219 94
E-Mail: [email protected]
Web: http://www.auerswald.de
--------------------------------------------------------------
Auerswald GmbH & Co. KG, Vor den Grashöfen 1, 38162 Cremlingen
Registriert beim AG Braunschweig HRA 13289
p.h.G Auerswald Geschäftsführungsges. mbH
Registriert beim AG Braunschweig HRB 7463
Geschäftsführer: Dipl-Ing. Gerhard Auerswald
On Mon, 15 Jun 2009 10:36:05 +0200
Wolfgang Mües <[email protected]> wrote:
> Am Samstag, 13. Juni 2009 schrieb Pierre Ossman:
> > For SD there are several checks
> > before the switch command is actually issued.
>
> But there are two cases not covered by these checks:
>
> a) the switch command is supported, but the card is not capable of switching
> to 50 MHz.
>
But a successful switch command (even if the response is that the card
cannot do it) should not need the checks you added. The switch data
structure is checked further down.
> b) the card rejects the switch command in SPI mode, because it is not
> mandatory here.
I cannot see anything in the spec backing up this claim.
Rgds
--
-- Pierre Ossman
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