The purpose of this series is too improve reliability of the amlogic mmc driver on new (g12a) and old ones (axg, gxl, gxbb, etc...) * The 3 first patches are just harmless clean ups. * Patch 4 makes sure HS400 can't be enabled, we still have not been able to crack this modes. * Patch 5 removes some clock glitches when switching to DDR modes * Patch 6 and 7 changes the tuning method from Rx phase to signal resampling. It could have been done in a single patch but the unified diff was extremely ugly. The change has been split in two patches to ease review. The last tuning update that went through was meant to improve the axg support. Since then, it was reported to break some other boards, like the s912 vim2. Also with the current tuning method, it was impossible to find phase settings which would work on all the SoCs, including the new ones. After redoing all the tests from scratch, it appeared that Rx phase made (strangely) almost no difference, especially on g12a and axg. However, it showed that it is important to have a phase shift between the Core and Tx clock, 180 works best. I discussed the test results with Amlogic. They suggested to use 180/0 or 0/180 for the Core and Tx phase. For tuning, they suggested to use signal resampling. So far, so good ... here the platform and modes tested: NanoPi-K2 (S905): SD UHS SDR50/DDR50, SDIO HS Odroid-C2 (S905): SD UHS SDR50/DDR50, eMMC DDR52/HS200 (16GB module) Khadas Vim (S905X): SD HS, SDIO HS, eMMC HS200 Libretech CC (S905X): SD HS, eMMC HS200 Khadas Vim2 (S912): SD HS, SDIO HS, eMMC HS200 S400 (A113D): SDIO UHS SDR104, eMMC DDR52/HS200 U200 (S905D2): SD HS, eMMC DDR52/HS200 SEI510 (S905X2): SD HS, eMMC DDR52/HS200 Changes since v1 [0]: * Add missing writel in patch 5 (error when switching width) * Change patch 3 commit description [0]: https://lkml.kernel.org/r/20190417204355.469-1-jbrunet@xxxxxxxxxxxx Jerome Brunet (7): mmc: meson-gx: remove open coded read with timeout mmc: meson-gx: ack only raised irq mmc: meson-gx: correct irq flag mmc: meson-gx: disable HS400 mmc: meson-gx: avoid clock glitch when switching to DDR modes mmc: meson-gx: remove Rx phase tuning mmc: meson-gx: add signal resampling tuning drivers/mmc/host/meson-gx-mmc.c | 419 +++++++++----------------------- 1 file changed, 114 insertions(+), 305 deletions(-) -- 2.20.1
