Andrew Morton wrote:
On Fri, 19 Mar 2010 08:24:56 +0200
Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote:
From: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Date: Fri, 19 Mar 2010 08:06:54 +0200
Subject: [PATCH] mmc: fix incorrect interpretation of card type bits
In the extended CSD register the CARD_TYPE is an 8-bit value
of which the upper 6 bits were reserved in JEDEC specifications
prior to version 4.4. In version 4.4 two of the reserved bits
were designated for identifying support for the newly added
High-Speed Dual Data Rate. Unfortunately the mmc_read_ext_csd()
function required that the reserved bits be zero instead of
ignoring them as it should.
This patch makes mmc_read_ext_csd() ignore the CARD_TYPE bits
that are reserved or not yet supported. It also stops the
function jumping to the end as though an error occurred, when
it is only warns that the CARD_TYPE bits (that it does interpret)
are invalid.
I need to whine about the changelog again.
I'm guessing that the effect here is that if someone puts one of these
new cards into an old kernel, this card will be incorrectly handled.
Perhaps in ways which render the whole thing useless.
This is for eMMC so that will not happen.
If that was a good guess then this patch would be needed in earlier
kernels too.
But it was only a guess, and I'd prefer not to have to guess. So
please do remember to explain things like this in the changelog?
OK. "Backport not necessary."
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