On 24.01.19 12:31, Andre Przywara wrote:
On Thu, 24 Jan 2019 12:21:17 +0100 Alexander Graf agraf@suse.de wrote:
On 24.01.19 12:07, Andre Przywara wrote:
On Thu, 24 Jan 2019 11:59:32 +0100 Alexander Graf agraf@suse.de wrote:
On 24.01.19 11:57, Andre Przywara wrote:
On Thu, 24 Jan 2019 11:17:03 +0100 Alexander Graf agraf@suse.de wrote:
On 22.01.19 17:37, Alexander Graf wrote: > > > On 22.01.19 17:28, Alexander Graf wrote: >> >> >> On 22.01.19 17:17, Oskari Lemmelä wrote: >>> Hi, >>> >>> On 22.1.2019 16.54, Alexander Graf wrote: >>>> >>>> On 05.01.19 18:52, Oskari Lemmela wrote: >>>>> Minimal changes to support sun6i based Allwinner SOCs >>>>> Changes are based to SPL driver >>>>> arch/arm/mach-sunxi/spl_spi_sunxi.c >>>>> >>>>> Signed-off-by: Oskari Lemmela oskari@lemmela.net >>>> I just tried to see if this patch gives me "sf" access on a >>>> SoPine system. Unfortunately, it seems as if the sun4i_spi >>>> driver doesn't even get probed? >>>> >>>> How did you manage to actually make use of this driver? >>>> >>>> >>>> Alex >>> >>> You need to add spi0 alias to dts and enable needed drivers to >>> defconfig. You can take look from Jagan's patch [1]. >>> >>> I didn't include those changes as Maxime already commented [2] >>> that Kconfig depends/defaults should be modified first. >> >> I don't see any relation between the dts change and the Kconfig >> dependency issues? >> >> But thanks for the pointer, I'll give this patch a try. > > Ok, so I now get the SPI controller initialized, but it seems to > only returns zeros when trying to access the SPI flash device. > > In other words, it doesn't work for me :). But maybe I'm missing > all the other clk patches to actually get it working?
Ok, so turns out the problem is that you can't have eMMC and SPI both working. I don't quite know yet whether this is just a pinmux problem (so potentially software workaroundable) or if it's a hardware limitation (eMMC pulling a line required for SPI).
The line that is shared is "DS", which is only needed for higher (e)MMC modes (HS-400). At the moment neither Linux nor U-Boot implement this mode, and probably U-Boot will never need it: it adds software complexity for a questionable performance benefit, especially if the flash chips can't keep up with the high interface speed anyway.
We addressed this in the DTs (kernel commit fa59dd2ef755).
I am a bit puzzled here as why this happens: I can't find where U-Boot would configure PC1 to use the MMC2 function: the hard-coded mmc_pinmux_setup() doesn't touch PC1 at all. Maybe it's the BootROM configuring this line? So we would need to reset it?
As I don't have an eMMC module here at hand right now, this has to wait till tonight for further insights.
A few more data points:
When I boot w/o eMMC module attached, SPI flash works When I then plug in the eMMC module, SPI flash still works
Plug in with power off (which you should always do)? So it goes through the BootROM?
When I that start initializing the eMMC module, SPI flash fails
What do you mean by that, exactly? Accessing eMMC from U-Boot?
Yes, "mmc part" to be precise.
Because that is the interesting data point, somehow this makes the eMMC module drive the pin.
When I then unplug the eMMC module, SPI flash works again
Again, at runtime?
Yup, all of it at runtime. I felt darey and ignored the fact that you should really only plug the eMMC module at boot time ;).
The last step definitely did not change pinmux. Hence the conclusion that this is line drive collision, not pinmux.
So I guess you're saying that forcing the eMMC into 4-DAT mode would make things work?
Technically DS is for HS-400, which is a step beyond 8-bit bus width. So just enabling 8 bit should not affect the DS line. There is a bit in the MMC controller to enable HS-400, but I don't see that we would set it (we actually don't even define the register). You could try to force eMMC to 4 bit to check this theory, by hack-removing the MMC_MODE_8BIT line in sunxi_mmc_init() in drivers/mmc/sunxi-mmc.c (we don't use DM_MMC yet, so it's in the hacky part and ignores the DT property)
Ok, that did not help. I guess the next best useful thing to do now would be to measure what the MISO line shows in each situation. Unfortunately I don't have my oscilloscope handy :).
Alex