helios64: restore hs400 support after enabling strobe line internal p…

…ulldown

Since v5.11, Linux upstream commit 8b5c2b45b8f0 disabled the internal pull-down
for the strobe line explicitly instead of leaving it in its default
state (the opposite of Rockchip Kernel which force enable this intrnal
pulldown by default) thus causing I/O errors in HS400 mode for various
eMMC modules (the ones that did not have an external pulldown on the
strobe line likely).
Discussed upstream and the choice has been made to keep this
behavior as it has been there for too long and reverting might break
other boards http://lists.infradead.org/pipermail/linux-rockchip/2024-April/046416.html

HS400 for helios64 was disabled in commit 5f2e23e
"Disabled hs400 on Helios64 (hopefully only temporarily) (#3126)"
but for 5.10.63i (ie before the above commit disabled internal pulldown).
Back then I had bisected the emmc I/O issue to a double init of the emmc
regulator introduced while adding deferred support to the regulator driver
core, ie commit 06653ebc0ad2 "regulator: core: resolve supply for boot-on/always-on regulators"
in 5.10.60. But due to the new default for the strobe line internal  pulldown
introduced in 5.6.11 when this double voltage regulator init issue was fixed likely by
8a866d527ac0 "regulator: core: Resolve supply name earlier to prevent double-init"
in Linux 6.1.

patch/kernel/archive/rockchip64-6.12/add-board-helios64.patch

@@ -358,7 +358,7 @@ index 111111111111..222222222222 100644
  };
 
  &cpu_l0 {
-@@ -275,6 +467,20 @@ &cpu_l3 {
+@@ -275,6 +467,21 @@ &cpu_l3 {
  	cpu-supply = <&vdd_cpu_l>;
  };
 
@@ -377,6 +377,7 @@ index 111111111111..222222222222 100644
 +};
 +
  &emmc_phy {
++	rockchip,enable-strobe-pulldown;
  	status = "okay";
  };
 @@ -295,6 +501,11 @@ &gmac {
@@ -813,7 +814,7 @@ index 111111111111..222222222222 100644
  		};
  	};
  };
-@@ -505,10 +981,29 @@ &pwm1 {
+@@ -505,10 +981,28 @@ &pwm1 {
  	status = "okay";
  };
 
@@ -834,9 +835,8 @@ index 111111111111..222222222222 100644
 +	assigned-clock-rates = <150000000>;
  	bus-width = <8>;
  	mmc-hs200-1_8v;
-+	// hs400 is broken on Helios64 since 5.10.60
-+	// mmc-hs400-1_8v;
-+	// mmc-hs400-enhanced-strobe;
++	mmc-hs400-1_8v;
++	mmc-hs400-enhanced-strobe;
 +	supports-emmc;
  	non-removable;
 +	disable-wp;

patch/kernel/archive/rockchip64-6.13/add-board-helios64.patch

@@ -338,7 +338,7 @@ index 111111111111..222222222222 100644
  };
 
  &cpu_l0 {
-@@ -275,6 +447,20 @@ &cpu_l3 {
+@@ -275,6 +447,21 @@ &cpu_l3 {
  	cpu-supply = <&vdd_cpu_l>;
  };
 
@@ -357,6 +357,7 @@ index 111111111111..222222222222 100644
 +};
 +
  &emmc_phy {
++	rockchip,enable-strobe-pulldown;
  	status = "okay";
  };
 @@ -295,6 +481,11 @@ &gmac {
@@ -793,7 +794,7 @@ index 111111111111..222222222222 100644
  		};
  	};
  };
-@@ -505,10 +961,29 @@ &pwm1 {
+@@ -505,10 +961,28 @@ &pwm1 {
  	status = "okay";
  };
 
@@ -814,9 +815,8 @@ index 111111111111..222222222222 100644
 +	assigned-clock-rates = <150000000>;
  	bus-width = <8>;
  	mmc-hs200-1_8v;
-+	// hs400 is broken on Helios64 since 5.10.60
-+	// mmc-hs400-1_8v;
-+	// mmc-hs400-enhanced-strobe;
++	mmc-hs400-1_8v;
++	mmc-hs400-enhanced-strobe;
 +	supports-emmc;
  	non-removable;
 +	disable-wp;