From a4b2e6063cfeaab1160501acfb27e8618a7c693f Mon Sep 17 00:00:00 2001 From: Marek Vasut Date: Thu, 15 Dec 2022 16:20:23 +0100 Subject: [PATCH] firmware: xilinx: Clear IOCTL_SET_SD_TAPDELAY using PM_MMIO_WRITE In case the tap delay required by Arasan SDHCI is set to 0, the current embeddedsw firmware unconditionally writes IOU_SLCR SD_ITAPDLY to 0x100 (SD0_ITAPDLYENA=1, SD0_ITAPDLYSEL=0). Previous behavior was to keep the IOU_SLCR SD_ITAPDLY set to 0x0. There is some sort of difference in the behavior between SD0_ITAPDLYENA=1/0 with the same SD0_ITAPDLYSEL=0, even though the behavior should be identical -- zero delay added to rxclk_in line. The former breaks HS200 training in low temperature conditions. Write IOU_SLCR SD_ITAPDLY register to 0 using PM_MMIO_WRITE which seem to allow unrestricted WRITE access (and PM_MMIO_READ which allows read access) to the entire address space. This way, it is possible to work around the defect in IOCTL_SET_SD_TAPDELAY design which does not permit clearing SDx_ITAPDLYENA bit. Note that the embeddedsw firmware does not permit clearing the SD_ITAPDLY SD0_ITAPDLYENA bit, this bit can only ever be set by the firmware and it is often impossible to update the possibly broken firmware. Signed-off-by: Marek Vasut Link: https://lore.kernel.org/r/20221215152023.8387-1-marex@denx.de Signed-off-by: Michal Simek --- drivers/firmware/xilinx/zynqmp.c | 27 +++++++++++++++++++++++++-- include/linux/firmware/xlnx-zynqmp.h | 4 ++++ 2 files changed, 29 insertions(+), 2 deletions(-) diff --git a/drivers/firmware/xilinx/zynqmp.c b/drivers/firmware/xilinx/zynqmp.c index 129f68d..acd83d2 100644 --- a/drivers/firmware/xilinx/zynqmp.c +++ b/drivers/firmware/xilinx/zynqmp.c @@ -738,8 +738,31 @@ EXPORT_SYMBOL_GPL(zynqmp_pm_get_pll_frac_data); */ int zynqmp_pm_set_sd_tapdelay(u32 node_id, u32 type, u32 value) { - return zynqmp_pm_invoke_fn(PM_IOCTL, node_id, IOCTL_SET_SD_TAPDELAY, - type, value, NULL); + u32 reg = (type == PM_TAPDELAY_INPUT) ? SD_ITAPDLY : SD_OTAPDLYSEL; + u32 mask = (node_id == NODE_SD_0) ? GENMASK(15, 0) : GENMASK(31, 16); + + if (value) { + return zynqmp_pm_invoke_fn(PM_IOCTL, node_id, + IOCTL_SET_SD_TAPDELAY, + type, value, NULL); + } + + /* + * Work around completely misdesigned firmware API on Xilinx ZynqMP. + * The IOCTL_SET_SD_TAPDELAY firmware call allows the caller to only + * ever set IOU_SLCR SD_ITAPDLY Register SD0_ITAPDLYENA/SD1_ITAPDLYENA + * bits, but there is no matching call to clear those bits. If those + * bits are not cleared, SDMMC tuning may fail. + * + * Luckily, there are PM_MMIO_READ/PM_MMIO_WRITE calls which seem to + * allow complete unrestricted access to all address space, including + * IOU_SLCR SD_ITAPDLY Register and all the other registers, access + * to which was supposed to be protected by the current firmware API. + * + * Use PM_MMIO_READ/PM_MMIO_WRITE to re-implement the missing counter + * part of IOCTL_SET_SD_TAPDELAY which clears SDx_ITAPDLYENA bits. + */ + return zynqmp_pm_invoke_fn(PM_MMIO_WRITE, reg, mask, 0, 0, NULL); } EXPORT_SYMBOL_GPL(zynqmp_pm_set_sd_tapdelay); diff --git a/include/linux/firmware/xlnx-zynqmp.h b/include/linux/firmware/xlnx-zynqmp.h index b986e26..eb88b4b 100644 --- a/include/linux/firmware/xlnx-zynqmp.h +++ b/include/linux/firmware/xlnx-zynqmp.h @@ -79,6 +79,10 @@ #define EVENT_ERROR_PSM_ERR1 (0x28108000U) #define EVENT_ERROR_PSM_ERR2 (0x2810C000U) +/* ZynqMP SD tap delay tuning */ +#define SD_ITAPDLY 0xFF180314 +#define SD_OTAPDLYSEL 0xFF180318 + enum pm_api_cb_id { PM_INIT_SUSPEND_CB = 30, PM_ACKNOWLEDGE_CB = 31, -- 2.7.4