Original architecture clock code from where this driver was derived did not
include nothing related to mmc clocks. OpenWRT people started to use mtk-sd
upstream driver recently and they were forced to use a dts 'fixed-clock'
node with 48 MHz clock:
- https://github.com/openwrt/openwrt/pull/15896
The proper thing to do to avoid that is to add the mmc related clocks to the
driver to avoid a dts with fixed clocks nodes. The minimal documentation in
the mt7620 programming guide says that there is a BBP_PLL clock of 480 MHz
derived from the 40 MHz XTAL and from there a clock divider by ten produces
the desired SDHC clock of 48 MHz for the mmc. Hence add a fixed clock 'bbppll'
and factor clock 'sdhc' ten divider child to properly set the 'mmc' peripheral
clock with the desired 48 Mhz rate.

Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
---
 drivers/clk/ralink/clk-mtmips.c | 30 +++++++++++++++++++++++-------
 1 file changed, 23 insertions(+), 7 deletions(-)

diff --git a/drivers/clk/ralink/clk-mtmips.c b/drivers/clk/ralink/clk-mtmips.c
index 76285fbbdeaa..97b8ca0f9181 100644
--- a/drivers/clk/ralink/clk-mtmips.c
+++ b/drivers/clk/ralink/clk-mtmips.c
@@ -207,6 +207,7 @@ static struct mtmips_clk mt7620_pherip_clks[] = {
 	{ CLK_PERIPH("10000b00.spi", "bus") },
 	{ CLK_PERIPH("10000b40.spi", "bus") },
 	{ CLK_PERIPH("10000c00.uartlite", "periph") },
+	{ CLK_PERIPH("10130000.mmc", "sdhc") },
 	{ CLK_PERIPH("10180000.wmac", "xtal") }
 };
 
@@ -220,6 +221,7 @@ static struct mtmips_clk mt76x8_pherip_clks[] = {
 	{ CLK_PERIPH("10000c00.uart0", "periph") },
 	{ CLK_PERIPH("10000d00.uart1", "periph") },
 	{ CLK_PERIPH("10000e00.uart2", "periph") },
+	{ CLK_PERIPH("10130000.mmc", "sdhc") },
 	{ CLK_PERIPH("10300000.wmac", "xtal") }
 };
 
@@ -272,8 +274,13 @@ static struct mtmips_clk_fixed rt3352_fixed_clocks[] = {
 	CLK_FIXED("periph", "xtal", 40000000)
 };
 
+static struct mtmips_clk_fixed mt7620_fixed_clocks[] = {
+	CLK_FIXED("bbppll", "xtal", 480000000)
+};
+
 static struct mtmips_clk_fixed mt76x8_fixed_clocks[] = {
-	CLK_FIXED("pcmi2s", "xtal", 480000000),
+	CLK_FIXED("bbppll", "xtal", 480000000),
+	CLK_FIXED("pcmi2s", "bbppll", 480000000),
 	CLK_FIXED("periph", "xtal", 40000000)
 };
 
@@ -328,6 +335,15 @@ static struct mtmips_clk_factor rt305x_factor_clocks[] = {
 	CLK_FACTOR("bus", "cpu", 1, 3)
 };
 
+static struct mtmips_clk_factor mt7620_factor_clocks[] = {
+	CLK_FACTOR("sdhc", "bbppll", 1, 10)
+};
+
+static struct mtmips_clk_factor mt76x8_factor_clocks[] = {
+	CLK_FACTOR("bus", "cpu", 1, 3),
+	CLK_FACTOR("sdhc", "bbppll", 1, 10)
+};
+
 static int mtmips_register_factor_clocks(struct clk_hw_onecell_data *clk_data,
 					 struct mtmips_clk_priv *priv)
 {
@@ -811,10 +827,10 @@ static const struct mtmips_clk_data rt5350_clk_data = {
 static const struct mtmips_clk_data mt7620_clk_data = {
 	.clk_base = mt7620_clks_base,
 	.num_clk_base = ARRAY_SIZE(mt7620_clks_base),
-	.clk_fixed = NULL,
-	.num_clk_fixed = 0,
-	.clk_factor = NULL,
-	.num_clk_factor = 0,
+	.clk_fixed = mt7620_fixed_clocks,
+	.num_clk_fixed = ARRAY_SIZE(mt7620_fixed_clocks),
+	.clk_factor = mt7620_factor_clocks,
+	.num_clk_factor = ARRAY_SIZE(mt7620_factor_clocks),
 	.clk_periph = mt7620_pherip_clks,
 	.num_clk_periph = ARRAY_SIZE(mt7620_pherip_clks),
 };
@@ -824,8 +840,8 @@ static const struct mtmips_clk_data mt76x8_clk_data = {
 	.num_clk_base = ARRAY_SIZE(mt76x8_clks_base),
 	.clk_fixed = mt76x8_fixed_clocks,
 	.num_clk_fixed = ARRAY_SIZE(mt76x8_fixed_clocks),
-	.clk_factor = rt305x_factor_clocks,
-	.num_clk_factor = ARRAY_SIZE(rt305x_factor_clocks),
+	.clk_factor = mt76x8_factor_clocks,
+	.num_clk_factor = ARRAY_SIZE(mt76x8_factor_clocks),
 	.clk_periph = mt76x8_pherip_clks,
 	.num_clk_periph = ARRAY_SIZE(mt76x8_pherip_clks),
 };
-- 
2.25.1

Quoting Sergio Paracuellos (2024-09-09 21:40:24)
> Original architecture clock code from where this driver was derived did not
> include nothing related to mmc clocks. OpenWRT people started to use mtk-sd
> upstream driver recently and they were forced to use a dts 'fixed-clock'
> node with 48 MHz clock:
> - https://github.com/openwrt/openwrt/pull/15896
> The proper thing to do to avoid that is to add the mmc related clocks to the
> driver to avoid a dts with fixed clocks nodes. The minimal documentation in
> the mt7620 programming guide says that there is a BBP_PLL clock of 480 MHz
> derived from the 40 MHz XTAL and from there a clock divider by ten produces
> the desired SDHC clock of 48 MHz for the mmc. Hence add a fixed clock 'bbppll'
> and factor clock 'sdhc' ten divider child to properly set the 'mmc' peripheral
> clock with the desired 48 Mhz rate.
> 
> Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
> ---

Applied to clk-next