[PATCH 07/10] mci: sdhci: rockchip: set TX-path source-select bit in DWCMSHC_EMMC_DLL_TXCLK

[Sascha Hauer]

Linux's sdhci-of-dwcmshc has, since rk3588 support was added in 2022,
unconditionally OR'd DLL_RXCLK_NO_INVERTER << DWCMSHC_EMMC_DLL_RXCLK_SRCSEL
(bit 29) into the DWCMSHC_EMMC_DLL_TXCLK write that follows DLL lock
in the high-speed path. Despite its name, position 29 in this
register controls a TX-path source-select; the constant just happens
to share the SRCSEL shift with the RX path register.

Barebox was never writing this bit. The omission was harmless on
controllers where the RX path's matching write (a few lines earlier
in this function) already sets the same bit position 29 - because on
those parts both clock paths end up with a working source-select.
The bit is needed for the TX path to have a working source-select in
its own right, however; the next commit's revision split, which
correctly stops setting the RX-path bit on rk3588 silicon, would
otherwise leave the TX path with no source-select at all and break
eMMC writes.

Match Linux's behaviour: set the bit unconditionally in the TXCLK
write.

Assisted-by: Claude Opus 4.7 <noreply at anthropic.com>
Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
---
 drivers/mci/rockchip-dwcmshc-sdhci.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/mci/rockchip-dwcmshc-sdhci.c b/drivers/mci/rockchip-dwcmshc-sdhci.c
index 23c887e906..fa2d9964a5 100644
--- a/drivers/mci/rockchip-dwcmshc-sdhci.c
+++ b/drivers/mci/rockchip-dwcmshc-sdhci.c
@@ -212,6 +212,7 @@ static void rk_sdhci_set_clock(struct rk_sdhci_host *host, unsigned int clock)
 
 	extra = DWCMSHC_EMMC_DLL_DLYENA |
 		DLL_TXCLK_TAPNUM_FROM_SW |
+		DLL_RXCLK_NO_INVERTER << DWCMSHC_EMMC_DLL_RXCLK_SRCSEL |
 		txclk_tapnum;
 	sdhci_write32(&host->sdhci, DWCMSHC_EMMC_DLL_TXCLK, extra);
 

-- 
2.47.3