Messages in this thread Patch in this message | | | From | Marc Pignat <> | Subject | Re: [PATCH 3/6] atmel-mci: Optional controller reset before every command | Date | Wed, 17 Jun 2009 10:32:22 +0200 |
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Hi!
On Wednesday 17 June 2009 02:54:36 Rob Emanuele wrote: > This patch adds the compile time configuration option for the atmel-mci driver to reset the Atmel MCI controller before every command. > > This is sometimes needed for the Atmel controller / board to function properly. > > Signed-off-by: Rob Emanuele <rob@emanuele.us> > --- > drivers/mmc/host/Kconfig | 10 ++++++++++ > drivers/mmc/host/atmel-mci.c | 11 ++++++++++- > 2 files changed, 20 insertions(+), 1 deletions(-) > > diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig > index a0eaf69..5875125 100644 > --- a/drivers/mmc/host/Kconfig > +++ b/drivers/mmc/host/Kconfig > @@ -161,6 +161,16 @@ config MMC_ATMELMCI > > endchoice > > +config MMC_ATMELMCI_ALWAYS_RESET > + bool "Reset before every request. Sometimes needed for buggy chips." > + depends on MMC_ATMELMCI > + help > + There are reports that some buggy controllers work better > + with a reset before every command. This may improve your > + controller's reliability. > + > + If unsure, say N. > + > config MMC_ATMELMCI_DMA > bool "Atmel MCI DMA support (EXPERIMENTAL)" > depends on MMC_ATMELMCI && AVR32 && DMA_ENGINE && EXPERIMENTAL > diff --git a/drivers/mmc/host/atmel-mci.c b/drivers/mmc/host/atmel-mci.c > index 98b25de..e5894f6 100644 > --- a/drivers/mmc/host/atmel-mci.c > +++ b/drivers/mmc/host/atmel-mci.c > @@ -63,6 +63,15 @@ struct atmel_mci_dma { > #endif > }; > > +/* > + * Configuration options from the kernel config > + */ > +#ifdef CONFIG_MMC_ATMELMCI_ALWAYS_RESET > +#define MMC_ALWAYS_RESET 1 > +#else > +#define MMC_ALWAYS_RESET 0 > +#endif
Some chips are known to hang after (some) transfer. There is no need for this configuration option, I think we should just do :
#define MMC_ALWAYS_RESET (cpu_is_at91rm9200() || add_your_cpu_name_here())
> + > /** > * struct atmel_mci - MMC controller state shared between all slots > * @lock: Spinlock protecting the queue and associated data. > @@ -720,7 +729,7 @@ static void atmci_start_request(struct atmel_mci *host, > host->completed_events = 0; > host->data_status = 0; > > - if (host->need_reset) { > + if (host->need_reset || MMC_ALWAYS_RESET) { > mci_writel(host, CR, MCI_CR_SWRST); > mci_writel(host, CR, MCI_CR_MCIEN); > mci_writel(host, MR, host->mode_reg);
Another option is to always reset the controller.
The reset operation won't hurt, it is simple and fast, and the code will be simpler and better tested.
Best regards
Marc
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