Date: Sat, 18 Oct 2014 19:01:07 +0000 (UTC) From: Luiz Otavio O Souza <loos@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r273264 - head/sys/arm/broadcom/bcm2835 Message-ID: <201410181901.s9IJ17LF003707@svn.freebsd.org>
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Author: loos Date: Sat Oct 18 19:01:07 2014 New Revision: 273264 URL: https://svnweb.freebsd.org/changeset/base/273264 Log: Add a workaround needed to fix a bug of Arasan Host Controller where it may lose the contents of consecutive writes (that happens within two SD card clock cycles). This fixes the causes of instability during the SD card detection and identification on Raspberry Pi (which happens at 400 kHz and so was much more vulnerable to this issue). Remove the previous workaround which clearly can't provide the same effect. MFC after: 1 week Relnotes: yes Modified: head/sys/arm/broadcom/bcm2835/bcm2835_sdhci.c Modified: head/sys/arm/broadcom/bcm2835/bcm2835_sdhci.c ============================================================================== --- head/sys/arm/broadcom/bcm2835/bcm2835_sdhci.c Sat Oct 18 18:27:24 2014 (r273263) +++ head/sys/arm/broadcom/bcm2835/bcm2835_sdhci.c Sat Oct 18 19:01:07 2014 (r273264) @@ -312,21 +312,15 @@ RD4(struct bcm_sdhci_softc *sc, bus_size static inline void WR4(struct bcm_sdhci_softc *sc, bus_size_t off, uint32_t val) { - bus_space_write_4(sc->sc_bst, sc->sc_bsh, off, val); - if ((off != SDHCI_BUFFER && off != SDHCI_INT_STATUS && off != SDHCI_CLOCK_CONTROL)) - { - int timeout = 100000; - while (val != bus_space_read_4(sc->sc_bst, sc->sc_bsh, off) - && --timeout > 0) - continue; - - if (timeout <= 0) - printf("sdhci_brcm: writing 0x%X to reg 0x%X " - "always gives 0x%X\n", - val, (uint32_t)off, - bus_space_read_4(sc->sc_bst, sc->sc_bsh, off)); - } + bus_space_write_4(sc->sc_bst, sc->sc_bsh, off, val); + /* + * The Arasan HC has a bug where it may lose the content of + * consecutive writes to registers that are within two SD-card + * clock cycles of each other (a clock domain crossing problem). + */ + if (sc->sc_slot.clock > 0) + DELAY(((2 * 1000000) / sc->sc_slot.clock) + 1); } static uint8_t
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