Hi Ulf, On Thu, Feb 08, 2018 at 10:31:39PM +0100, Ulf Hansson wrote: > On 8 February 2018 at 15:59, Quentin Schulz <quentin.schulz@xxxxxxxxxxx> wrote: > > Hi Ulf, > > > > On Wed, Aug 30, 2017 at 03:43:49PM +0200, Ulf Hansson wrote: > >> On 30 August 2017 at 14:44, Hans de Goede <hdegoede@xxxxxxxxxx> wrote: > >> > Hi, > >> > > >> > > >> > On 21-07-17 16:35, Quentin Schulz wrote: > >> >> > >> >> From: Hans de Goede <hdegoede@xxxxxxxxxx> > >> >> > >> >> Some sdio devices have a multiple stage bring-up process. Specifically > >> >> the esp8089 (for which an out of tree driver is available) loads firmware > >> >> on the first call to its sdio-drivers' probe function and then resets > >> >> the device causing it to reboot from its RAM with the new firmware. > >> >> > >> >> When this sdio device reboots it comes back up in 1 bit 400 KHz mode > >> >> again, and we need to walk through the whole ios negatiation and sdio > >> >> setup > >> >> again. > >> >> > >> >> There are 2 problems with this: > >> >> > >> >> 1) Typically these devices are soldered onto some (ARM) tablet / SBC > >> >> PCB and as such are described in devicetree as "non-removable", which > >> >> causes the mmc-core to scan them only once and not poll for the device > >> >> dropping of the bus. Normally this is the right thing todo but in the > >> >> eso8089 example we need the mmc-core to notice the module has disconnected > >> >> (since it is now in 1 bit mode again it will not talk to the host in 4 bit > >> >> mode). This can be worked around by using "broken-cd" in devicetree > >> >> instead of "non-removable", but that is not a proper fix since the device > >> >> really is non-removable. > >> >> > >> >> 2) When the mmc-core detects the device has disconnected it will poweroff > >> >> the device, causing the RAM loaded firmware to be lost. This can be worked > >> >> around in devicetree by using regulator-always-on (and avoiding the use of > >> >> mmc-pwrseq), but again that is more of a hack then a proper fix. > >> >> > >> >> This commmit fixes 1) by adding a mmc_force_detect_change function which > >> >> will cause scanning for device removal / insertion until a new device is > >> >> detected. 2) Is fixed by a keep_power flag to the mmc_force_detect_change > >> >> function which when set causes the mmc-core to keep the power to the > >> >> device > >> >> on during the rescan. > >> >> > >> >> Cc: Icenowy Zheng <icenowy@xxxxxxxx> > >> >> Cc: Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx> > >> >> Cc: Chen-Yu Tsai <wens@xxxxxxxx> > >> >> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> > >> > > >> > > >> > So when I posted this patch quite a while back, there was some discussion > >> > about this and a consensus that this is not the right solution. > >> > > >> > So first of all lets describe the problem: > >> > > >> > The esp8089 sdio wifi chip is really an ARM core with a wifi phy > >> > connected to it (as many wifi chipsets are). > >> > > >> > But this one comes up in some really generic sdio capable boot-loader > >> > mode and we need to feed it firmware and then reboot it into the > >> > new firmware. > >> > > >> > The reboot is where the problems happens. It seems to fallback > >> > from the negotiated 4 wire sdio mode to single wire spi mode then. > >> > > >> > The out of tree version of the driver deals with this by not setting > >> > the non-removable flag as well as setting the broken_cd flag so that > >> > the mmc core polls the device, after the reboot the poll fails > >> > because the mmc-controller and the esp8089 are using a different > >> > amount of wires so the mmc-cmd the poll uses times out. > >> > > >> > After which the esp8089 drivers remove function gets called, and > >> > the mmc stack re-discovers the esp8089 by restarting the whole > >> > number of wires (and speed) used negotiation. After which the > >> > esp8089 driver's probe function gets called (again) and on > >> > firmware loading is has set a global flag, so now it actually > >> > acts as a wifi driver rather then trying to load the firmware > >> > a second time. > >> > > >> > Since I did not want to rely on broken_cd polling I came up > >> > with the hack which is this patch. > >> > > >> > So when this patch was first discussed we came to the conclusion > >> > that what we really need is some sort of mmc_reprobe_device > >> > function which the driver can call from probe which will > >> > redo the number of wires (and speed) used negotiation, > >> > while keeping the sdio_function device as is so that probe can > >> > simply continue after this and we also don't need the ugly > >> > global flag. > >> > > >> > The idea would be for this function to be some wrapper > >> > around mmc_init_card() which resets the ios settings as is > >> > normally done on remove and then call mmc_init_card() > >> > passing in the existing card the same way as is done > >> > one resume, so that the existing card / sdio_function > >> > devices get reused. > >> > > >> > IIRC Ulf would look into writing this mmc_reprobe_device > >> > function and then I would test it with the esp8089, but > >> > Ulf never got around to writing the function and I ended > >> > up working on other things too. > >> > >> Thanks for summary! > >> > >> Just to let you know, I haven't forgot about this problem. I am > >> planning for a major update of the SDIO for power management support, > >> within a not too far future. > >> The issue described above, is then also one of the things I also plan > >> to look into. > >> > > > > I'd like to know if any progress has been made on that problem (I may > > have missed patches). > > Had you had the time to look at the issue? > > I have looked at the issue, but not manage to cook some patches for it. > > However, it's on my top of my TODO list for mmc. No promises, but > perhaps and hopefully I manage to get something posted during the > coming release cycle. > Cool! If you ever need some testing, I'd be glad to test your patches (even if they are in a draft/RFC state). Also, when you send patches, I'd appreciate being Cc'ed so that I can put my Tested-by :) Thanks! Best regards, Quentin
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