On Thu, 1 Jul 2021, at 13:10, Joel Stanley wrote: > On Fri, 25 Jun 2021 at 06:10, Andrew Jeffery <andrew@xxxxxxxx> wrote: > > > > The degree values were reversed out from the magic tap values of 7 (in) > > and 15 + inversion (out) initially suggested by Aspeed. > > > > With the patch tacoma survives several gigabytes of reads and writes > > using dd while without it locks up randomly during the boot process. > > > > Signed-off-by: Andrew Jeffery <andrew@xxxxxxxx> > > Thanks for the fix. Is this required due to "mmc: sdhci-of-aspeed: Add > AST2600 bus clock support" or "mmc: sdhci-of-aspeed: Expose clock > phase controls"? Sort of neither, it's really a bug with the devicetrees. > > On the topic of those patches, it would be good if we could operate > the devices (with the slower speed?) when the device tree does not > provide the phase values. Think about system bringup, or where you > need the system booting in order to determine the phase calculations. You can use the maximum-frequency binding to make things go slow enough to paper over phase issues. This helped us limp along early on. https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/mmc/mmc-controller.yaml?h=v5.13#n90 But really it depends on how bad the issues are at a given speed. > > What changes would be required to the host driver for it to work out of the box? Maybe the above is enough of a crutch? Andrew
