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Message-ID: <20160823220442.GA20351@zach-desktop>
Date: Tue, 23 Aug 2016 17:04:43 -0500
From: Zach Brown <zach.brown@...com>
To: Haibo Chen <haibo.chen@....com>
CC: "adrian.hunter@...el.com" <adrian.hunter@...el.com>,
"ulf.hansson@...aro.org" <ulf.hansson@...aro.org>,
"mark.rutland@....com" <mark.rutland@....com>,
"robh+dt@...nel.org" <robh+dt@...nel.org>,
"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] sdhci: Add quirk and device tree parameter to force SD
test mode
On Tue, Aug 23, 2016 at 01:34:20AM +0000, Haibo Chen wrote:
> > -----Original Message-----
> > From: linux-mmc-owner@...r.kernel.org [mailto:linux-mmc-
> > owner@...r.kernel.org] On Behalf Of Zach Brown
> > Sent: Tuesday, August 23, 2016 6:56 AM
> > To: adrian.hunter@...el.com
> > Cc: ulf.hansson@...aro.org; mark.rutland@....com; robh+dt@...nel.org;
> > linux-mmc@...r.kernel.org; devicetree@...r.kernel.org; linux-
> > kernel@...r.kernel.org
> > Subject: [PATCH] sdhci: Add quirk and device tree parameter to force SD test
> > mode
> >
> > From: Jaeden Amero <jaeden.amero@...com>
> >
> > On some devices, CD is broken so that we must force the SDHCI into test mode
> > and set CD, so that it always detects an SD card as present.
> >
> > In order to get a device with broken CD working, we had previously always set
> > the SDHCI into test mode. Unfortunately, this had the side effect of making all
> > SD cards used with our Linux kernels undetectable and non-removable.
>
> Why not use the poll mode? You can set the flag MMC_CAP_NEEDS_POLL, then
> the mmc core will detect the card every second.
>
We're using a Xilinx Zynq device. In an AR they state:
"Signals card detect (CDn) and write protect (WPn) are required for the Zynq SD
card interface to work." http://www.xilinx.com/support/answers/61064.html
So polling won't work, since the interface itself won't work unless CDn is on.
Test mode allows us to get the interface working with no CDn signal.
> >
> > By making this "SD test mode" setting optional via a quirk, we can avoid this
> > side effect for devices other than the device with broken CD.
> > Additionally, we add a device parameter to sdhci-pltfm to allow all SDHCI
> > drivers to enable this quirk.
> >
> > Signed-off-by: Jaeden Amero <jaeden.amero@...com>
> > Signed-off-by: Zach Brown <zach.brown@...com>
> > ---
> > Documentation/devicetree/bindings/mmc/mmc.txt | 2 ++
> > drivers/mmc/host/sdhci-pltfm.c | 4 ++++
> > drivers/mmc/host/sdhci.c | 9 +++++++++
> > drivers/mmc/host/sdhci.h | 4 ++++
> > 4 files changed, 19 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/mmc/mmc.txt
> > b/Documentation/devicetree/bindings/mmc/mmc.txt
> > index 22d1e1f..3a9be41 100644
> > --- a/Documentation/devicetree/bindings/mmc/mmc.txt
> > +++ b/Documentation/devicetree/bindings/mmc/mmc.txt
> > @@ -52,6 +52,8 @@ Optional properties:
> > - no-sdio: controller is limited to send sdio cmd during initialization
> > - no-sd: controller is limited to send sd cmd during initialization
> > - no-mmc: controller is limited to send mmc cmd during initialization
> > +- force-sd-cd-test-mode: card detection is broken on device, force cd
> > +test
> > + enable and cd test inserted so host will always detect a card.
> >
> > *NOTE* on CD and WP polarity. To use common for all SD/MMC host
> > controllers line polarity properties, we have to fix the meaning of the "normal"
> > and "inverted"
> > diff --git a/drivers/mmc/host/sdhci-pltfm.c b/drivers/mmc/host/sdhci-pltfm.c
> > index 1d17dcf..056d101 100644
> > --- a/drivers/mmc/host/sdhci-pltfm.c
> > +++ b/drivers/mmc/host/sdhci-pltfm.c
> > @@ -87,6 +87,10 @@ void sdhci_get_of_property(struct platform_device
> > *pdev)
> > if (of_get_property(np, "broken-cd", NULL))
> > host->quirks |= SDHCI_QUIRK_BROKEN_CARD_DETECTION;
> >
> > + if (of_get_property(np, "force-sd-cd-test-mode", NULL))
> > + host->quirks2 |=
> > + SDHCI_QUIRK2_MUST_FORCE_SD_CD_TEST_MODE;
> > +
> > if (of_get_property(np, "no-1-8-v", NULL))
> > host->quirks2 |= SDHCI_QUIRK2_NO_1_8_V;
> >
> > diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c index
> > cd65d47..2f4c6f9 100644
> > --- a/drivers/mmc/host/sdhci.c
> > +++ b/drivers/mmc/host/sdhci.c
> > @@ -117,6 +117,15 @@ static inline bool sdhci_data_line_cmd(struct
> > mmc_command *cmd) static void sdhci_set_card_detection(struct sdhci_host
> > *host, bool enable) {
> > u32 present;
> > + u8 ctrl;
> > +
> > + if (host->quirks2 & SDHCI_QUIRK2_MUST_FORCE_SD_CD_TEST_MODE)
> > {
> > + /* Put the card in test mode, with card inserted */
> > + ctrl = sdhci_readl(host, SDHCI_HOST_CONTROL);
> > + ctrl |= SDHCI_CTRL_CD_TEST_INSERTED |
> > + SDHCI_CTRL_CD_TEST_ENABLE;
> > + sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL);
> > + }
> >
> > if ((host->quirks & SDHCI_QUIRK_BROKEN_CARD_DETECTION) ||
> > !mmc_card_is_removable(host->mmc))
> > diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h index
> > 0411c9f..dd609b2 100644
> > --- a/drivers/mmc/host/sdhci.h
> > +++ b/drivers/mmc/host/sdhci.h
> > @@ -84,6 +84,8 @@
> > #define SDHCI_CTRL_ADMA32 0x10
> > #define SDHCI_CTRL_ADMA64 0x18
> > #define SDHCI_CTRL_8BITBUS 0x20
> > +#define SDHCI_CTRL_CD_TEST_INSERTED 0x40
> > +#define SDHCI_CTRL_CD_TEST_ENABLE 0x80
> >
> > #define SDHCI_POWER_CONTROL 0x29
> > #define SDHCI_POWER_ON 0x01
> > @@ -422,6 +424,8 @@ struct sdhci_host {
> > #define SDHCI_QUIRK2_ACMD23_BROKEN (1<<14)
> > /* Broken Clock divider zero in controller */
> > #define SDHCI_QUIRK2_CLOCK_DIV_ZERO_BROKEN (1<<15)
> > +/* Controller must support device with broken CD */
> > +#define SDHCI_QUIRK2_MUST_FORCE_SD_CD_TEST_MODE (1<<16)
> >
> > int irq; /* Device IRQ */
> > void __iomem *ioaddr; /* Mapped address */
> > --
> > 2.7.4
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the
> > body of a message to majordomo@...r.kernel.org More majordomo info at
> > http://vger.kernel.org/majordomo-info.html
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