Links to https://forums.raspberrypi.com/viewtopic.php?t=381663

For reference, driver changes and overlay changes need to be in separate patches.

The overlay can be an override on the existing imx219 overlay to reduce duplication. My diff (which I can't test) doing that was

diff --git a/arch/arm/boot/dts/overlays/imx219-overlay.dts b/arch/arm/boot/dts/overlays/imx219-overlay.dts
index 4c4bcd309a3d..3411d5bbd8ce 100644
--- a/arch/arm/boot/dts/overlays/imx219-overlay.dts
+++ b/arch/arm/boot/dts/overlays/imx219-overlay.dts
@@ -65,6 +65,21 @@ csi_ep: endpoint {
                };
        };
 
+       fragment@201 {
+               target = <&csi_ep>;
+               __dormant__ {
+                       data-lanes = <1 2 3 4>;
+               };
+       };
+
+       fragment@202 {
+               target = <&cam_endpoint>;
+               __dormant__ {
+                       data-lanes = <1 2 3 4>;
+                       link-frequencies =
+                               /bits/ 64 <363000000>;
+       };
+
        __overrides__ {
                rotation = <&cam_node>,"rotation:0";
                orientation = <&cam_node>,"orientation:0";
@@ -77,6 +92,7 @@ __overrides__ {
                       <&vcm>, "VANA-supply:0=", <&cam0_reg>;
                vcm = <&vcm>, "status=okay",
                      <&cam_node>,"lens-focus:0=", <&vcm>;
+               4lane = <0>, "+201+202";
        };
 };

There's a missing line (another closing brace and semicolon) in the proposed fragment 202, but otherwise it looks okay.

Removed overlay changes from this PR and updated driver based on 6by9's suggestion

Can you give us a Signed-off-by line for the changes in your PRs (this and #6580)? Mine would be: Signed-off-by: Phil Elwell <[email protected]>

Done for both!

Any comments, @6by9?

I'd hoped to test with a module, but it got stuck in customs (hopefully arriving tomorrow).

Commit message could be fuller, and include Fixes: ceddfd4493b3 ("media: i2c: imx219: Support four-lane operation"), but I can do that when upstreaming it.

Do the pixel rate numbers work out for frame rate control?
That upstream commit changes the pixel rate to 280.8MPix/s (from 184.2) and link frequency of 363MHz (from 456MHz). Both those numbers come from section "9-2 clock setting example" in the datasheet (see https://github.com/rellimmot/Sony-IMX219-Raspberry-Pi-V2-CMOS/blob/master/RASPBERRY%20PI%20CAMERA%20V2%20DATASHEET%20IMX219PQH5_7.0.0_Datasheet_XXX.PDF).

sohonomura2020's post at https://forums.raspberrypi.com/viewtopic.php?p=2283325#p2283325 implies the new IMX219_REG_PLL_VT_MPY should be 0x57 = 87 and IMX219_REG_PLL_OP_MPY should be 0x5a = 90. Your patch has 88 and 91.

My maths says that IMX219_REG_PLL_OP_MPY = 91 gives a link rate of 364MHz, whilst 90 gives a link rate of 360MHz. Neither is the driver value of 363MHz.
Likewise for IMX219_REG_PLL_VT_MPY, =88 gives a pixel rate of 281.6MPix/s, whilst 87 gives a pixel rate of 278.4MPix/s. Neither is the driver value of 280.8MPix/s.
So whilst your numbers will improve matters, they still look slightly off. Frame rates and exposure times will likewise be slightly wrong.

The example does say EXCK_FREQ = 12MHz.
702/12 = 58.5, so I think the only way that the example timings can be achieved is by INCK=12MHz, Pre-Div1 = 2, and then PLL_VT_MPY = 117.
We have INCK = 24MHz. There is no Pre-Div1 option of /4 listed (although it is defined as an 8 bit register, so might be worth a quick test), so I don't think the numbers can be achieved.

Continuing the search, registers 0x110A/B are listed as max_pre_pll_clk_div / "Maximum Pre PLL divider value" with a value of 0x0D (14 decimal), so perhaps /4 is permitted. That would be worth a test, as amending the link frequency is a pain (we'd have to log a warning for the approximation if asked for the previously "supported" value).