Messages in this thread Patches in this message | | | Date | Tue, 9 Apr 2013 09:18:12 +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 04/08/2013 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:
diff --git a/drivers/mmc/host/mxs-mmc.c b/drivers/mmc/host/mxs-mmc.c index 206fe49..2a3b9c9 100644 --- a/drivers/mmc/host/mxs-mmc.c +++ b/drivers/mmc/host/mxs-mmc.c @@ -679,15 +682,20 @@ static int mxs_mmc_probe(struct platform_device *pdev) /* set mmc core parameters */ mmc->ops = &mxs_mmc_ops; mmc->caps = MMC_CAP_SD_HIGHSPEED | MMC_CAP_MMC_HIGHSPEED | - MMC_CAP_SDIO_IRQ | MMC_CAP_NEEDS_POLL; + MMC_CAP_SDIO_IRQ;
of_property_read_u32(np, "bus-width", &bus_width); if (bus_width == 4) 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, "non-removable", NULL)) + mmc->caps |= MMC_CAP_NONREMOVABLE; + else + mmc->caps |= MMC_CAP_NEEDS_POLL; + + host->wp_gpio = of_get_named_gpio_flags(np, "wp-gpios", 0, &flags); if (flags & OF_GPIO_ACTIVE_LOW) host->wp_inverted = 1;
In theory, and according to the mmc bindings doc, this flag must assume the card is always present. However the MMC core function mmc_rescan() will still call at least once the get_cd() hook, which in the mxs-mmc.c returns the value of the CD line. In my platform (where the CD line is not connected) this is returning 0, so I needed to do the following:
diff --git a/drivers/mmc/host/mxs-mmc.c b/drivers/mmc/host/mxs-mmc.c index 206fe49..2a3b9c9 100644 --- a/drivers/mmc/host/mxs-mmc.c +++ b/drivers/mmc/host/mxs-mmc.c @@ -95,6 +95,9 @@ 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 (mmc->caps & MMC_CAP_NONREMOVABLE) + return 1; + return !(readl(ssp->base + HW_SSP_STATUS(ssp)) & BM_SSP_STATUS_CARD_DETECT); } to return a 1 when the driver should assume that the card is there. I wonder however if this should be a global mmc patch instead, and have mmc_rescan() not call the host get_cd() hook at all if MMC_CAP_NONREMOVABLE is set.
Regards, -- 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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