Re: [PATCH v4 3/4] mmc: dw_mmc-rockchip: Skip all phases bigger than 270 degrees

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Hello Detlev,

On 2024-08-22 23:15, Detlev Casanova wrote:
From: Shawn Lin <shawn.lin@xxxxxxxxxxxxxx>

Per design recommendation, it'd better not try to use any phase
which is bigger than 270. Let's officially follow this.

Would it be possible to provide a reference to the actual design
specification?  This change affects all users of the dw_mmc-rockchip
driver, so in case any regressions are found later, having as much
detail as possible can only be beneficial.

Signed-off-by: Shawn Lin <shawn.lin@xxxxxxxxxxxxxx>
(cherry picked from commit 2a53aab5cfa43065b2e979959d727332a8a03c03)
Signed-off-by: Detlev Casanova <detlev.casanova@xxxxxxxxxxxxx>
---
 drivers/mmc/host/dw_mmc-rockchip.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/mmc/host/dw_mmc-rockchip.c
b/drivers/mmc/host/dw_mmc-rockchip.c
index 2748f9bf2691..1458cb5fd5c7 100644
--- a/drivers/mmc/host/dw_mmc-rockchip.c
+++ b/drivers/mmc/host/dw_mmc-rockchip.c
@@ -310,6 +310,9 @@ static int dw_mci_rk3288_execute_tuning(struct
dw_mci_slot *slot, u32 opcode)

 	/* Try each phase and extract good ranges */
 	for (i = 0; i < priv->num_phases; ) {
+		/* Cannot guarantee any phases larger than 270 would work well */
+		if (TUNING_ITERATION_TO_PHASE(i, priv->num_phases) > 270)
+			break;
 		rockchip_mmc_set_phase(host, true,
 				       TUNING_ITERATION_TO_PHASE(
 						i,




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