diff options
Diffstat (limited to 'target/linux/bcm27xx/patches-6.6/950-1192-dts-rp1-hobble-DMA-AXI-burst-lengths.patch')
| -rw-r--r-- | target/linux/bcm27xx/patches-6.6/950-1192-dts-rp1-hobble-DMA-AXI-burst-lengths.patch | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/target/linux/bcm27xx/patches-6.6/950-1192-dts-rp1-hobble-DMA-AXI-burst-lengths.patch b/target/linux/bcm27xx/patches-6.6/950-1192-dts-rp1-hobble-DMA-AXI-burst-lengths.patch new file mode 100644 index 0000000000..9cfdefec7d --- /dev/null +++ b/target/linux/bcm27xx/patches-6.6/950-1192-dts-rp1-hobble-DMA-AXI-burst-lengths.patch @@ -0,0 +1,35 @@ +From 4c1a665b465fa0e9d3369a467fc563ec812a47ce Mon Sep 17 00:00:00 2001 +From: Jonathan Bell <jonathan@raspberrypi.com> +Date: Fri, 19 Jul 2024 13:07:59 +0100 +Subject: [PATCH 1192/1215] dts: rp1: hobble DMA AXI burst lengths + +Channels 1-2 have a statically configured maximum MSIZE of 8, and +channels 3-8 have MSIZE set to 4. The DMAC "helpfully" silently +truncates bursts to the hardware supported maximum, so any FIFO read +operation with an oversized burst threshold will leave a residue of +threshold minus MSIZE rows. + +As channel allocation is dynamic, this means every client needs to use a +maximum of 4 for burst length. + +AXI AWLEN/ARLEN constraints aren't strictly related to MSIZE, except +that bursts won't be issued that are longer than MSIZE beats. Therefore, +it's a useful proxy to tell clients of the DMAC the hardware +limitations. + +Signed-off-by: Jonathan Bell <jonathan@raspberrypi.com> +--- + arch/arm64/boot/dts/broadcom/rp1.dtsi | 2 +- + 1 file changed, 1 insertion(+), 1 deletion(-) + +--- a/arch/arm64/boot/dts/broadcom/rp1.dtsi ++++ b/arch/arm64/boot/dts/broadcom/rp1.dtsi +@@ -1064,7 +1064,7 @@ + snps,data-width = <4>; // (8 << 4) == 128 bits + snps,block-size = <0x40000 0x40000 0x40000 0x40000 0x40000 0x40000 0x40000 0x40000>; + snps,priority = <0 1 2 3 4 5 6 7>; +- snps,axi-max-burst-len = <8>; ++ snps,axi-max-burst-len = <4>; + status = "disabled"; + }; + |