Messages in this thread Patch in this message | | | Date | Tue, 9 Apr 2013 11:00:09 +0200 | From | Hector Palacios <> | Subject | Re: [PATCH RFC] ARM: dts: mxs: leave card detect out of common mmc pins config |
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Dear Marek Vasut,
On 04/09/2013 10:15 AM, Marek Vasut wrote: > Dear Hector Palacios, > >> Dear Marek Vasut, >> >> On 04/08/2013 06:28 PM, Marek Vasut wrote: >>> Dear Shawn Guo, >>> >>>> On Mon, Apr 08, 2013 at 03:58:05PM +0200, Hector Palacios wrote: >>>>> On 04/08/2013 02:48 PM, Shawn Guo wrote: >>>>>> On Mon, Apr 08, 2013 at 12:12:20PM +0200, Hector Palacios wrote: >>>>>>> MicroSD card sockets don't usually have card detect line. This pin >>>>>>> is actually not needed for the MMC to work and it is more of a >>>>>>> platform design decission to have it. >>>>>>> The card detect pin already has a configuration entry of its own: >>>>>>> 'mmc0_cd_cfg' so we complete the iomux configuration here and let >>>>>>> platforms to include it or not depending on whether the card detect >>>>>>> line is routed to the SD socket. >>>>>> >>>>>> Sounds sensible. >>>>>> >>>>>>> Signed-off-by: Hector Palacios <hector.palacios@digi.com> >>>>>>> --- >>>>>>> >>>>>>> Hello, >>>>>>> >>>>>>> All imx28 based platforms except 'bluegiga,apx4devkit' and >>>>>>> 'schulercontrol,imx28-sps1', use 'mmc0_cd_cfg' in their mmc >>>>>>> configuration so please check whether this patch would break these >>>>>>> platforms. >>>>>> >>>>>> I just tested the patch on imx28-evk and card-detection still works. >>>>>> So patches applied, thanks. >>>>> >>>>> The EVK and most platforms will work because they are using >>>>> 'mmc0_cd_cfg' so actually this patch does not change anything on >>>>> them. >>>>> Platforms 'bluegiga,apx4devkit' and 'schulercontrol,imx28-sps1' >>>>> however are not referencing 'mmc0_cd_cfg' so after applying this >>>>> patch they will have unconfigured CD line and they may break. >>>> >>>> Ah, yes. I thought that any board that has CD support has to reference >>>> 'mmc0_cd_cfg'. That's not necessarily true. >>>> >>>>> The driver will call get_cd() upon probing, which returns the status of >>>>> the CD line. Please check these two platforms before applying. >>>> >>>> Ok, let's wait for people owning the boards to confirm. >>> >>> Maybe you want to use MMC_CAP_NEEDS_POLL as was noted by someone before >>> on the olinuxino -- the slot is there, it's just the CD line that's >>> missing. >> >> I'm not sure of what you mean. The mxs-mmc.c driver already sets the >> MMC_CAP_NEEDS_POLL flag by default in the probe() function. My platform >> does not even route the CD line because the microSD socket does not have >> it. >> So what I have done is modify the driver to parse the property >> 'non-removable' from the device tree in order to set the >> MMC_CAP_NONREMOVABLE flag: > > Yes, I get it. I have two remarks still: > 1) The card is removable (you can pull it out from olinuxino's slot)
True, I misunderstood the use of 'non-removable'. So I guess I could use 'broken-cd' property instead, right?
> 2) Why is the NEEDS_POLL set by default ?
Because the CD line cannot cause an interrupt in this controller.
> 3) Does the NEEDS_POLL not solve the issue with missing CD line?
No. CD polling relies on the status register. The field CARD_DETECT in HW_SSP_STATUS register directly reflects the state of the SSP_DETECT input pin. If the pin is not connected it can have any value, so I guess we need a custom flag on the driver:
diff --git a/drivers/mmc/host/mxs-mmc.c b/drivers/mmc/host/mxs-mmc.c index 206fe49..ec0874b 100644 --- a/drivers/mmc/host/mxs-mmc.c +++ b/drivers/mmc/host/mxs-mmc.c @@ -72,6 +72,7 @@ struct mxs_mmc_host { int sdio_irq_en; int wp_gpio; bool wp_inverted; + bool cd_broken; };
static int mxs_mmc_get_ro(struct mmc_host *mmc) @@ -95,6 +96,9 @@ static int mxs_mmc_get_cd(struct mmc_host *mmc) struct mxs_mmc_host *host = mmc_priv(mmc); struct mxs_ssp *ssp = &host->ssp;
+ if (host->cd_broken) + return 1; + return !(readl(ssp->base + HW_SSP_STATUS(ssp)) & BM_SSP_STATUS_CARD_DETECT); } @@ -686,8 +690,11 @@ static int mxs_mmc_probe(struct platform_device *pdev) mmc->caps |= MMC_CAP_4_BIT_DATA; else if (bus_width == 8) mmc->caps |= MMC_CAP_4_BIT_DATA | MMC_CAP_8_BIT_DATA; - host->wp_gpio = of_get_named_gpio_flags(np, "wp-gpios", 0, &flags);
+ if (of_find_property(np, "broken-cd", NULL)) + host->cd_broken = 1; + + host->wp_gpio = of_get_named_gpio_flags(np, "wp-gpios", 0, &flags); if (flags & OF_GPIO_ACTIVE_LOW) host->wp_inverted = 1;
Thank you for your comments. -- Héctor Palacios -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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