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Re: CVS commit: src/sys/dev/sdmmc
On Jul 17, 2012, at 5:39 AM, Greg Troxel wrote:
> Modified Files:
> src/sys/dev/sdmmc: sdhc.c
> Log Message:
> Handle interrupt acknowledgement in the SDHC_FLAG_32BIT_ACCESS case in
> the same way as non-SDHC_FLAG_32BIT_ACCESS case.
> To generate a diff of this commit:
> cvs rdiff -u -r1.20 -r1.21 src/sys/dev/sdmmc/sdhc.c
> Two questions, one of which isn't about your change.
> It seems that the HREAD4 of SDHC_NINTR_STATUS is reading both that and
> SDHC_EINTR_STATUS, but it seems odd that those are addresses 0x30 and
> 0x32, which don't seem 4-byte aligned. So is it really ok to do an
> HREAD4 across boundaries like that? It seems odd, but maybe it's about
> the bus and the chip is fine with it.
0x30 is aligned and that is the address that is read from a 32-bit acccess.
> In the non-32 case, it seems that the EINTR register is read and then
> written back exactly if the error bit is set in the NINTR register. In
> the 32 case, it seems that the SDHC_ERROR_INTERRUPT bit is set in NINTR
> if any bits are set in EINTR, in addition to writing both.
> So while I see the point that the |= into status is effectively a dead
> it seems odd to have bits set in SDHC_EINTR_STATUS without
> SDHC_ERROR_INTERRUPT set in SDHC_NINTR_STATUS, and
> the two code paths seem different still
This is because the ESDHC doesn't set SDHC_ERROR_INTERRUPT in its
register since you've read SDHC_EINTR_STATUS and can see those bits
directly. So, for the sdhc driver, it needs to be emulated.
> I'm curious if you've been seeing bits in EINTR without ERROR in NINTR,
> and what the symptoms are that provoked this fix - I have a system with
> an sdhc (on evbppc/P2020) that mostly works but has occasional write
That is exactly what the ESDHC on the P2020 does.
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