Re: [PATCH v14 6/6] mmc: omap_hsmmc: Pin remux workaround to support SDIO interrupt on AM335x

[Tony Lindgren <tony@atomide.com>]

* Balaji T K <balajitk@ti.com> [140529 06:42]:
> On Thursday 29 May 2014 01:58 PM, Andreas Fenkart wrote:
> >The am335x can't detect pending cirq in PM runtime suspend.
> >This patch reconfigures dat1 as a GPIO before going to suspend.
> >SDIO interrupts are detected with the GPIO, the GPIO will only wake
> >the module from suspend, SDIO irq detection will still happen through the
> >IP block.
> >
> >Idea of remuxing the pins by Tony Lindgren. Code contributions from
> >Tony Lindgren and Balaji T K <balajitk@ti.com>
> >
> >Signed-off-by: Andreas Fenkart <afenkart@gmail.com>
> >Signed-off-by: Tony Lindgren <tony@atomide.com>
> 
> Acked-by: Balaji T K <balajitk@ti.com>
> 
> Hi Chris/Ulf,
> 
> Can you please queue this series for 3.16

Yes please, not seeing these in linux next yet.

Regards,

Tony
 
> >diff --git a/Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt b/Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt
> >index 0233ba7..76bf087 100644
> >--- a/Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt
> >+++ b/Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt
> >@@ -57,3 +57,56 @@ Examples:
> >  			&edma 25>;
> >  		dma-names = "tx", "rx";
> >  	};
> >+
> >+[workaround for missing swakeup on am33xx]
> >+
> >+This SOC is missing the swakeup line, it will not detect SDIO irq
> >+while in suspend.
> >+
> >+                             ------
> >+                             | PRCM |
> >+                              ------
> >+                               ^ |
> >+                       swakeup | | fclk
> >+                               | v
> >+       ------                -------               -----
> >+      | card | -- CIRQ -->  | hsmmc | -- IRQ -->  | CPU |
> >+       ------                -------               -----
> >+
> >+In suspend the fclk is off and the module is disfunctional. Even register reads
> >+will fail. A small logic in the host will request fclk restore, when an
> >+external event is detected. Once the clock is restored, the host detects the
> >+event normally. Since am33xx doesn't have this line it never wakes from
> >+suspend.
> >+
> >+The workaround is to reconfigure the dat1 line as a GPIO upon suspend. To make
> >+this work, we need to set the named pinctrl states "default" and "idle".
> >+Prepare idle to remux dat1 as a gpio, and default to remux it back as sdio
> >+dat1. The MMC driver will then toggle between idle and default state during
> >+runtime.
> >+
> >+In summary:
> >+1. select matching 'compatible' section, see example below.
> >+2. specify pinctrl states "default" and "idle", "sleep" is optional.
> >+3. specify the gpio irq used for detecting sdio irq in suspend
> >+
> >+If configuration is incomplete, a warning message is emitted "falling back to
> >+polling". Also check the "sdio irq mode" in /sys/kernel/debug/mmc0/regs. Mind
> >+not every application needs SDIO irq, e.g. MMC cards.
> >+
> >+	mmc1: mmc@48060100 {
> >+		compatible = "ti,am33xx-hsmmc";
> >+		...
> >+		pinctrl-names = "default", "idle", "sleep"
> >+		pinctrl-0 = <&mmc1_pins>;
> >+		pinctrl-1 = <&mmc1_idle>;
> >+		pinctrl-2 = <&mmc1_sleep>;
> >+		...
> >+		interrupts-extended = <&intc 64 &gpio2 28 0>;
> >+	};
> >+
> >+	mmc1_idle : pinmux_cirq_pin {
> >+		pinctrl-single,pins = <
> >+		        0x0f8 0x3f      /* GPIO2_28 */
> >+		>;
> >+	};
> >diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
> >index 0febb17..35ac2e4 100644
> >--- a/drivers/mmc/host/omap_hsmmc.c
> >+++ b/drivers/mmc/host/omap_hsmmc.c
> >@@ -1754,15 +1754,33 @@ static int omap_hsmmc_configure_wake_irq(struct omap_hsmmc_host *host)
> >  	 * and need to remux SDIO DAT1 to GPIO for wake-up from idle.
> >  	 */
> >  	if (host->pdata->controller_flags & OMAP_HSMMC_SWAKEUP_MISSING) {
> >-		ret = -ENODEV;
> >-		devm_free_irq(host->dev, host->wake_irq, host);
> >-		goto err;
> >+		struct pinctrl *p = devm_pinctrl_get(host->dev);
> >+		if (!p) {
> >+			ret = -ENODEV;
> >+			goto err_free_irq;
> >+		}
> >+		if (IS_ERR(pinctrl_lookup_state(p, PINCTRL_STATE_DEFAULT))) {
> >+			dev_info(host->dev, "missing default pinctrl state\n");
> >+			devm_pinctrl_put(p);
> >+			ret = -EINVAL;
> >+			goto err_free_irq;
> >+		}
> >+
> >+		if (IS_ERR(pinctrl_lookup_state(p, PINCTRL_STATE_IDLE))) {
> >+			dev_info(host->dev, "missing idle pinctrl state\n");
> >+			devm_pinctrl_put(p);
> >+			ret = -EINVAL;
> >+			goto err_free_irq;
> >+		}
> >+		devm_pinctrl_put(p);
> >  	}
> >
> >  	OMAP_HSMMC_WRITE(host->base, HCTL,
> >  			 OMAP_HSMMC_READ(host->base, HCTL) | IWE);
> >  	return 0;
> >
> >+err_free_irq:
> >+	devm_free_irq(host->dev, host->wake_irq, host);
> >  err:
> >  	dev_warn(host->dev, "no SDIO IRQ support, falling back to polling\n");
> >  	host->wake_irq = 0;
> >
>