Date: Thu, 22 Jan 2009 09:30:07 -0700 (MST) From: "M. Warner Losh" <imp@bsdimp.com> To: krassi@bulinfo.net Cc: freebsd-arm@freebsd.org Subject: Re: Mount root from SD card?(solved!) Message-ID: <20090122.093007.1785588956.imp@bsdimp.com> In-Reply-To: <497896F3.9030908@bulinfo.net> References: <49788702.9010808@FreeBSD.org> <20090122151340.GE50103@cicely7.cicely.de> <497896F3.9030908@bulinfo.net>
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In message: <497896F3.9030908@bulinfo.net> Krassimir Slavchev <krassi@bulinfo.net> writes: : Index: at91_mci.c : =================================================================== : --- at91_mci.c (revision 187590) : +++ at91_mci.c (working copy) : @@ -199,7 +199,7 @@ : goto out; : } : sc->host.f_min = 375000; : - sc->host.f_max = at91_master_clock / 2; /* Typically 30MHz */ : + sc->host.f_max = AT91C_MASTER_CLOCK / 2; /* Typically 30MHz */ : sc->host.host_ocr = MMC_OCR_320_330 | MMC_OCR_330_340; : if (sc->wire4) : sc->host.caps = MMC_CAP_4_BIT_DATA; This change is wrong. : @@ -399,8 +399,8 @@ : WR4(sc, MCI_ARGR, cmd->arg); : if (cmdr & MCI_CMDR_TRCMD_START) { : if (cmdr & MCI_CMDR_TRDIR) { : + WR4(sc, MCI_CMDR, cmdr); : WR4(sc, PDC_PTCR, PDC_PTCR_RXTEN); : - WR4(sc, MCI_CMDR, cmdr); This change is also wrong. It won't work. Also, why test the direction at all if we're just going to do the same thing in both legs of the branch? When I was developing the code, I originally had the 'send a command and then enable PDC' logic. It didn't work for the read case, so now we enable the reader and then send the command. We do this based on the logic that it is OK to have the PDC enabled when there's no data transfer going, but if we send the command, then take an interrupt before we can enable the PDC, we'd lose data. And that seemed to happen a lot. There's lots of races in programming this chip :( : } else { : WR4(sc, MCI_CMDR, cmdr); : WR4(sc, PDC_PTCR, PDC_PTCR_TXTEN); Warner
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