On Wed, Sep 14, 2016 at 12:05:19PM +0200, Hans de Goede wrote: > Hi, > > On 13-09-16 13:50, Maxime Ripard wrote: > >Hi, > > > >On Mon, Sep 12, 2016 at 04:47:49PM +0200, Hans de Goede wrote: > >>On 12-09-16 15:56, Maxime Ripard wrote: > >>>Hi, > >>> > >>>On Mon, Sep 12, 2016 at 01:53:24PM +0200, Ciprian Manea wrote: > >>>>I'm using a SinA33 dev board (Allwinner a33 SoC) and at the moment > >>>>I'm trying to boot from the eMMC. > >>>> > >>>>But it fails in the following way: > >>>> > >>>> > >>>>*Got the following error at boot time:* > >>>>*U-Boot SPL 2016.09-rc2-00125-g6e8b42f (Sep 08 2016 - 11:00:46) DRAM: 1024 > >>>>MiB Trying to boot from MMC2 MMC Device 1 not found spl: could not find > >>>>mmc > >>>>device. error: -19 SPL: failed to boot from all boot devices ### ERROR ### > >>>>Please RESET the board ###* > >>> > >>>So I've been on the same issue for the last couple of days. > >>> > >>>Since that board is already supported, adding support for the eMMC > >>>basically came down to that patch on top of 2016.09-rc2. > >>> > >>>http://code.bulix.org/kcgxri-106037?raw > >>> > >>>(Quite hackish, the 8-Bits part being a separate issue that would need > >>>to be addressed somehow). > >>> > >>>However, it doesn't work, neither when flashing u-boot on the eMMC > >>>itself (where there's a timeout error in the SPL) nor when trying to > >>>access the eMMC from a U-Boot loaded from the (external) SD. > >>> > >>>In the latter case, even mmc dev 1 fails silently. > >>> > >>>I traced that down to the mmc_switch here: > >>>http://git.denx.de/?p=u-boot.git;a=blob;f=drivers/mmc/mmc.c#l530 > >>> > >>>Which fails with ETIMEDOUT, and more specifically, it's the call to > >>>mmc_rint_wait here > >>>http://git.denx.de/?p=u-boot.git;a=blob;f=drivers/mmc/sunxi_mmc.c#l383 > >>>that times out. > >>> > >>>Increasing the timeout value (to 10000) doesn't really change > >>>anything. I guess this is also the reason why we had a timeout error > >>>in the SPL. > >>> > >>>This eMMC works fine in Linux, with the same muxing (and I guess the > >>>earlier commands wouldn't be successful if the muxing or power was not > >>>set up appropriately). So I'm kind of running out of ideas on what > >>>could be the root cause of this. > >>> > >>>Hans, any ideas? > >> > >>Maybe the emmc needs external pull-ups ? I don't remember if u-boot > >>always enables those or not ... > > > >So I pushed this a bit more, and it seems like commenting the call to > >mmc_change_freq makes everything just work. > > > >Reading the JEDEC spec, it looks like when you switch to high speed, > >you also need to change the controller clock rate, that u-boot doesn't > >seem to do at the moment, which obviously will fail, since the > >controller will be stuck at the former rate, while the eMMC would be > >switched. > > > >If I comment mmc_change_freq, everything works. > > Hmm, I'm pretty sure the u-boot sunxi mmc code > does properly change the clock, see mmc_set_mod_clk() in > drivers/mmc/sunxi_mmc.c > > This will switch to the right PLL, etc. So there likely is > something else going on making things not work at higher > speeds.
Yep, I noticed that. However, what confuses me more is that the command seems to be sent here: http://git.denx.de/?p=u-boot.git;a=blob;f=drivers/mmc/mmc.c#l530 And set_ios is being called after we check that everything works. Linux for example calls set_ios right after switching http://lxr.free-electrons.com/source/drivers/mmc/core/mmc.c#L965 > Maybe we need a higher driver strenghts at the mmc io pins, or maybe > we've a completely unrelated issue ? I've tested that already. It doesn't change the outcome. > I'm pretty sure that the eMMC's on A20 devices work fine in 50MHZ > (SDR) mode. What emmc was that? Did it support HS? Was it considered an SD (and went through sd_change_freq), or an MMC? Thanks, Maxime -- Maxime Ripard, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com
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