* NeilBrown <neilb@xxxxxxx> [150223 18:47]: > According to section 7.1.2 of > > http://www.sandisk.com/media/File/OEM/Manuals/SD_SDIO_specsv1.pdf > > In the case where the interrupt mechanism is used to wake the host while > the card is in a low power state (i.e. no clocks), Both the card and the > host shall be placed into the 1-bit SD mode prior to stopping the clock. > > This is particularly important for the Marvell "libertas" wifi chip > in the GTA04. While in 4-bit mode it will only signal an interrupt > when the clock is running (which is why setting CLKEXTFREE is > important). > In 1-bit mode, the interrupt is asynchronous (explained in OMAP3 > TRM description of the CIRQ flag to MMCHS_STAT: > > In 1-bit mode, interrupt source is asynchronous (can be a source of > asynchronous wakeup). > In 4-bit mode, interrupt source is sampled during the interrupt > cycle. > > ) > > It is awkward to simply set 1-bit mode in ->runtime_suspend > as that will call mmc_set_ios which calls ops->set_ios(), > which will likely call pm_runtime_get_sync(), on the device that > is currently suspending. This deadlocks. > > So: > - create a work_struct to schedule setting of 1-bit mode > - introduce an 'sdio_narrowed' state flag which transitions: > 0 (normal) -> 1 (convert to 1-bit pending) -> > 2 (have switch to 1-bit mode) -> 0 (normal) > - create a function mmc_sdio_want_no_clocks() which can be called > when the driver wants to turn off clocks (presumably after an > idle timeout). This either succeeds (in 1-bit mode) or fails > and schedules the work to switch to 1-bit mode. > - when the host is claimed, if sdio_narrowed is 2, restore the > 4-bit bus > - When the host is released, if sdio_narrowed is 1, then some > caller other than our worker claimed the host first, so > clear sdio_narrowed. > > This all allows a graceful and race-free switch to 1-bit mode > before switching off the clocks, if SDIO interrupts are enabled. > > A host should call mmc_sdio_want_no_clocks() when about to turn off > clocks if sdio interrupts are enabled, and the ->disable() function > should not use a timeout (pm_runtime_put_autosuspend) if > ->sdio_narrowed is 2. Wow! A mystery finally solved for why libertas_sdio using devices like overo won't work for the wakeirqs.. The interface has to be in 1-bit mode for libertas to produce any SDIO interrupts.. Below is a patch enabling some more SDIO wakeirqs. Seems to work on overo now too :) So tor the whole series, please feel free to add: Tested-by: Tony Lindgren <tony@xxxxxxxxxxx> 8< ------------------- From: Tony Lindgren <tony@xxxxxxxxxxx> Date: Thu, 26 Feb 2015 16:16:03 -0800 Subject: [PATCH] ARM: dts: Fix omap3 SDIO wakeirqs for devices using sdio_libertas Turns out the the MMC interface needs to be in 1-bit mode for the libertas card to send any SDIO interrupts as pointed out by NeilBrown <neilb@xxxxxxx>. Now that the MMC framework is getting fixed for setting 1-bit mode for idle, we can enable SDIO wakeirqs for libertas using devices too. Cc: Andreas Fenkart <afenkart@xxxxxxxxx> Cc: Ash Charles <ash@xxxxxxxxxxx> Cc: Florian Vaussard <florian.vaussard@xxxxxxx> Cc: NeilBrown <neil@xxxxxxxxxx> Signed-off-by: Tony Lindgren <tony@xxxxxxxxxxx> --- a/arch/arm/boot/dts/omap3-gta04.dtsi +++ b/arch/arm/boot/dts/omap3-gta04.dtsi @@ -367,6 +367,7 @@ }; &mmc2 { + interrupts-extended = <&intc 86 &omap3_pmx_core 0x12e>; vmmc-supply = <&vaux4>; bus-width = <4>; ti,non-removable; --- a/arch/arm/boot/dts/omap3-overo-base.dtsi +++ b/arch/arm/boot/dts/omap3-overo-base.dtsi @@ -185,6 +185,7 @@ &mmc2 { pinctrl-names = "default"; pinctrl-0 = <&mmc2_pins>; + interrupts-extended = <&intc 86 &omap3_pmx_core 0x12e>; vmmc-supply = <&w3cbw003c_npoweron>; vqmmc-supply = <&w3cbw003c_bt_nreset>; vmmc_aux-supply = <&w3cbw003c_wifi_nreset>; -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
