[PATCH 0/4] mmc: sdhci-cadence: SD6HC DDR50 read-path tuning and fixes

[tze.yee.ng@altera.com]

From: Tze Yee Ng <tze.yee.ng@altera.com>

This series enables DDR50 on the Cadence SD6HC (SD/eMMC v6) PHY. DDR50
has no CMD19 tuning, so the read path must be centred by static,
board/SoC-characterised PHY settings. Bringing it up on Agilex5 also
exposed PHY issues affecting the existing tuned modes.

  - Patch 1: add the post-tuning settle delay the PHY needs after the
    DLL re-locks, matching sdhci_cdns6_phy_init().
  - Patch 2: program PHONY_DQS_TIMING (left 0 in all modes); in
    extended-read DDR it must be the rebar pulse width in clk_phy cycles
    minus 1, else one DDR beat is duplicated.
  - Patch 3: document three optional SD6HC DDR50 read-path properties.
  - Patch 4: read those properties at probe and apply them in DDR50,
    and fix the DQS_TIMING read-modify-write so USE_LPBK_DQS is cleared
    before being reprogrammed.

The new cdns,ddr50-* properties are unused in this series; they will be
consumed by the socfpga_agilex5_socdk and socfpga_agilex5_socdk_emmc
device trees, submitted as a separate series.

Tested on Agilex5 SoCDK: SD DDR50 and eMMC DDR52.

Tze Yee Ng (4):
  mmc: sdhci-cadence6: add PHY settle delay after tuning DLL re-lock
  mmc: sdhci-cadence6: program PHONY_DQS_TIMING for extended-read DDR
  dt-bindings: mmc: cdns,sdhci: add SD6HC DDR50 read-path tuning
  mmc: sdhci-cadence: read SD6HC DDR50 tuning from device tree

 .../devicetree/bindings/mmc/cdns,sd6hc.yaml   | 27 ++++++
 drivers/mmc/host/sdhci-cadence-phy-v6.c       | 90 ++++++++++++++++++-
 2 files changed, 116 insertions(+), 1 deletion(-)

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2.43.7