On Tue, Dec 7, 2010 at 9:22 PM, Arnd Hannemann <arnd@xxxxxxxxxx> wrote: > Am 07.12.2010 00:39, schrieb Magnus Damm: >> On Tue, Dec 7, 2010 at 2:35 AM, Arnd Hannemann <arnd@xxxxxxxxxx> wrote: >>> This patch implements SDIO IRQ support for mfds which >>> announce the MMC_CAP_SDIO_IRQ capability for tmio_mmc. >>> Tested with a b43-based wireless SDIO card and sh_mobile_sdhi. >>> >>> This patch applies on top of: >>> mmc: tmio_mmc: allow multi-element scatter-gather lists >>> mmc: tmio_mmc: fix PIO fallback on DMA descriptor allocation failure >>> mmc: tmio: merge the private header into the driver >>> mmc: tmio: implement a bounce buffer for unaligned DMA >>> >>> Signed-off-by: Arnd Hannemann <arnd@xxxxxxxxxx> >>> CC: Ian Molton <ian@xxxxxxxxxxxxxx> >>> CC: Samuel Ortiz <sameo@xxxxxxxxxxxxxxx> >>> CC: Guennadi Liakhovetski <g.liakhovetski@xxxxxx> >>> --- >>> drivers/mmc/host/tmio_mmc.c | 54 ++++++++++++++++++++++++++++++++++++++++++- >>> 1 files changed, 53 insertions(+), 1 deletions(-) >> >> Thanks for your work on this! >> >> Just curious, did you test this change in 4-bit mode and/or 1-bit >> mode? I believe that 1-bit mode support is rather simple, but 4-bit >> mode requires toggling between the IRQ and DATA function which happen >> to be using the same pin. It looks like the current code only deals >> with 1-bit mode - perhaps 4-bit mode isn't supported by the b43 >> driver? > > Yes, I tested this in 1-bit and 4-bit mode. At least the card claims it is using it, > it says "width=2". I also read about the toggling, and expected to do > something fancy, but when tests where successful I came to the conclusion > that the controller does the toggling for us. Do you believe otherwise? Yes, I believe something more advanced is needed for 4-bit mode. But I don't really have any proof. I just know that I spent quite some time trying to get it to work and ended up staying in polling mode because enabling real IRQs seemed to require too much time. This was before some interrupt ack fixes so things may have improved since then. I also remember both testing on b43 hardware and AR6002. There are a couple of things against us at this point: a) b43 hardware may not be enough to test this are you really sure 4-bit mode is enabled? =) is the b43 driver doing multi-block data transfers? i believe IRQs work differently for multi-block data transfers and single-block. b) we don't have any public data sheet for the SDHI hardware block how good is that? c) the simplified SDIO spec is not exactly full of details: 8.1.3 Interrupt Period Definition This section is not included in the Simplified Specification. 8.1.4 Interrupt Period at the Data Block Gap in 4-bit SD Mode (Optional) This section is not included in the Simplified Specification. 8.1.5 Inhibited Interrupts (Removed Section) This section is not included in the Simplified Specification. 8.1.6 End of Interrupt Cycles This section is not included in the Simplified Specification. >> Not sure how the Linux MMC stack supports 4-bit IRQs, but the S4MI bit >> in the CCCR should specify if it's allowed to enable interrupts in >> between data transfers or not. Perhaps that is something we need to >> deal with in the driver? Or maybe the framework needs to be extended? > > I quick grep shows that nobody seems to care about this bit until now... Yeah, that seems to be the case. I guess it's a non-issue then. =) I'll try to find my AR6002 card, maybe that will shed some light... Thanks, / magnus -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
