On Fri, Jun 27, 2014 at 04:39:42PM +0200, Andreas Fenkart wrote: > I have an mwifiex module(sd8787) behind omap_hsmmc(am33xx-soc) > The module is non-removable wired fix to soc. Now the wifi module > needs 2 clocks; one is a sleep clock the other used when not > sleeping. > While the sleep clock is fixed, @32 kHz, the system clock can be > one out of several values, but can be be derived automatically > from the sleep clock. But this requires the clock to be present > when the wifi module comes out of reset. > > Another problem is software reboot, at initial power on the wifi > card will react to mmc discovery. After a software reset of the > host it will not, because it has already been disvovered and > didn't notice the host rebooted, unless we reset it as well. > While this seems obvious, the problem is that the reset is needed > before the card can be discovered. Which means we cannot move the > reset logic into the mwifiex driver, since that driver has not > yet been selected through vendor/product id. > we had same problem with sd8787 and a different system design. we added reset-gpios property [1] and used it in sdhci-pxav3.c [2] as sdhci_pxav3_toggle_reset_gpio() 1. http://code.coreboot.org/p/openfirmware/source/tree/HEAD/cpu/arm/olpc/sdhci.fth#L104 2. http://dev.laptop.org/git/olpc-kernel/tree/drivers/mmc/host/sdhci-pxav3.c?h=arm-3.5#n229 > the reset logic: > gpiod_set_value(card->gpiod_reset, 0); > clk_enable(card->sleep_clock); > udelay(1000); > gpiod_set_value(card->gpiod_reset, 1); > > The idea so far was to extend the device-tree node of the > mmc slot by some reset leafs; > > &mmc { > ti,non-removable; > .. > peripheral-clocks = <&clk &clk2 ...>; > peripheral-reset-gpios = <&gpio0 1 1 &gpio1 2 3 ...>; > } > > in mmc_add_host, all clocks will be enabled and gpios be pulled > low for 1 msec we used 5ms. > Is this a feasible solution? > > > Another related issue, is the card reset in mwifiex driver: > > static void sdio_card_reset_worker(struct work_struct *work) > { > struct mmc_host *target = reset_host; > > pr_err("Resetting card...\n"); > mmc_remove_host(target); > /* 20ms delay is based on experiment with sdhci controller */ > mdelay(20); > mmc_add_host(target); > } > static DECLARE_WORK(card_reset_work, sdio_card_reset_worker); > > There are obviously a lot of problems with this, e.g. custom debugfs > entries created in the driver will be lost. But sometimes this > code might avert disaster in case the command handlers between > driver and firmware lost synchronization > > How could this be done in a better way? i'm interested as well. -- James Cameron http://quozl.linux.org.au/ -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
