Hi, On Wed, Feb 08 2012, [email protected] wrote: > From: Jerry Huang <[email protected]> > > SD card read was failing (data crc error)on some cards at > maximum possible frequency on P1010(CCB frequency set to 400MHz). > Some clock deviations are also observed at this frequency. > Hence reduced the mmc clock freq. > > Signed-off-by: Priyanka Jain <[email protected]> > Singed-off-by: Jerry Huang <[email protected]> > CC: Chris Ball <[email protected]> > Acked-by: Anton Vorontsov <[email protected]>
Thanks, just one comment below: > --- > changes for v2: > - change the property to compatible for quirks > changes for v3: > - fix one compile error > changes for v4: > - use hooks to suspend/resume the special platform > changes for v5: > - add the Acked-by > changes for v6: > - move the workaround codes to special platform from header file > changes for v7: > - don't use quirks to check the platform support > > drivers/mmc/host/sdhci-of-esdhc.c | 19 ++++++++++++++++++- > 1 files changed, 18 insertions(+), 1 deletions(-) > drivers/mmc/host/sdhci-of-esdhc.c | 24 ++++++++++++++++++++++-- > 1 files changed, 22 insertions(+), 2 deletions(-) > > diff --git a/drivers/mmc/host/sdhci-of-esdhc.c > b/drivers/mmc/host/sdhci-of-esdhc.c > index 2ef52f4..acac541 100644 > --- a/drivers/mmc/host/sdhci-of-esdhc.c > +++ b/drivers/mmc/host/sdhci-of-esdhc.c > @@ -1,7 +1,7 @@ > /* > * Freescale eSDHC controller driver. > * > - * Copyright (c) 2007, 2010 Freescale Semiconductor, Inc. > + * Copyright (c) 2007, 2010, 2012 Freescale Semiconductor, Inc. > * Copyright (c) 2009 MontaVista Software, Inc. > * > * Authors: Xiaobo Xie <[email protected]> > @@ -14,6 +14,7 @@ > */ > > #include <linux/io.h> > +#include <linux/of.h> > #include <linux/delay.h> > #include <linux/module.h> > #include <linux/mmc/host.h> > @@ -114,6 +115,25 @@ static unsigned int esdhc_of_get_min_clock(struct > sdhci_host *host) > return pltfm_host->clock / 256 / 16; > } > > +static void esdhc_of_set_clock(struct sdhci_host *host, unsigned int clock) > +{ > + /* Workaround to reduce the clock frequency for p1010 esdhc */ > + if (of_find_compatible_node(NULL, NULL, "fsl,p1010-esdhc")) { > + if (clock == 0) { > + host->clock = clock; > + return; > + } Is this if (clock == 0) necessary? You'll be calling esdhc_set_clock() immediately afterwards, and it performs the same test. > + > + if (clock > 20000000) > + clock -= 5000000; > + if (clock > 40000000) > + clock -= 5000000; > + } > + > + /* Set the clock */ > + esdhc_set_clock(host, clock); > +} > + > #ifdef CONFIG_PM > static u32 esdhc_proctl; > static void esdhc_of_suspend(struct sdhci_host *host) > @@ -135,7 +155,7 @@ static struct sdhci_ops sdhci_esdhc_ops = { > .write_l = sdhci_be32bs_writel, > .write_w = esdhc_writew, > .write_b = esdhc_writeb, > - .set_clock = esdhc_set_clock, > + .set_clock = esdhc_of_set_clock, > .enable_dma = esdhc_of_enable_dma, > .get_max_clock = esdhc_of_get_max_clock, > .get_min_clock = esdhc_of_get_min_clock, Thanks, - Chris. -- Chris Ball <[email protected]> <http://printf.net/> One Laptop Per Child -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
