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mmc: dw_mmc-rockchip: Improve v2 tuning

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v2 tuning has a defect that if invalid space is laid
between 90 and 180, and the PVT might make the invalid
space back and forth. To overcome this weakness, we don't
need to select phase from beginning, and should directly
chose the next one against the last phase selected.

Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Change-Id: I0cbeb1dba524c2e23a3719d28b868af3ed49e20b
This commit is contained in:
Shawn Lin
2021-10-29 15:13:52 +08:00
committed by Tao Huang
parent a124131bab
commit 959a4d84f2
1 changed files with 15 additions and 8 deletions
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23
drivers/mmc/host/dw_mmc-rockchip.c
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@@ -143,22 +143,29 @@ static int dw_mci_v2_execute_tuning(struct dw_mci_slot *slot, u32 opcode)
struct dw_mci *host = slot->host;
struct dw_mci_rockchip_priv_data *priv = host->priv;
struct mmc_host *mmc = slot->mmc;
u32 degrees[4] = {90, 180, 270, 360};
u32 degrees[4] = {0, 90, 180, 270}, degree;
int i;
static bool inherit = true;
if (inherit) {
inherit = false;
i = clk_get_phase(priv->sample_clk) / 90 - 1;
i = clk_get_phase(priv->sample_clk) / 90;
degree = degrees[i];
goto done;
}
/* v2 only support 4 degrees in theory */
/*
* v2 only support 4 degrees in theory.
* First we inherit sample phases from firmware, which should
* be able work fine, at least in the first place.
* If retune is needed, we search forward to pick the last
* one phase from degree list and loop around until we get one.
* It's impossible all 4 fixed phase won't be able to work.
*/
for (i = 0; i < ARRAY_SIZE(degrees); i++) {
if (degrees[i] == priv->last_degree)
continue;
clk_set_phase(priv->sample_clk, degrees[i]);
degree = degrees[i] + priv->last_degree;
degree = degree % 360;
clk_set_phase(priv->sample_clk, degree);
if (!mmc_send_tuning(mmc, opcode, NULL))
break;
}
@@ -170,7 +177,7 @@ static int dw_mci_v2_execute_tuning(struct dw_mci_slot *slot, u32 opcode)
done:
dev_info(host->dev, "Successfully tuned phase to %d\n", degrees[i]);
priv->last_degree = degrees[i];
priv->last_degree = degree;
return 0;
}