openwrt/target/linux/bcm27xx/patches-6.6/950-0695-PCI-brcmstb-Change-RCB_-MPS-64B-_MODE-bits.patch

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From 96ebf0a9fc30646420af7ef5c273b81d35a78a75 Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.com>
Date: Wed, 1 Nov 2023 10:13:29 +0000
Subject: [PATCH 0695/1085] PCI: brcmstb: Change RCB_{MPS,64B}_MODE bits
Upstream commit [1] unconditionally sets the RCB_MPS and RCB_64B bits
that govern where packets are split. We think this is potentially
harmful, particularly on CM4 and Pi 5 where potentially any PCIe devices
could be attached.
Make RCB_MPS conditional on a DT property and never set RCB_64B.
[1] commit 602fb860945f ("PCI: brcmstb: Set RCB_{MPS,64B}_MODE bits")
Signed-off-by: Phil Elwell <phil@raspberrypi.com>
---
drivers/pci/controller/pcie-brcmstb.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
--- a/drivers/pci/controller/pcie-brcmstb.c
+++ b/drivers/pci/controller/pcie-brcmstb.c
@@ -336,6 +336,7 @@ struct brcm_pcie {
struct device_node *np;
bool ssc;
bool l1ss;
+ bool rcb_mps_mode;
int gen;
u64 msi_target_addr;
struct brcm_msi *msi;
@@ -1196,14 +1197,14 @@ static int brcm_pcie_setup(struct brcm_p
/*
* Set SCB_MAX_BURST_SIZE, CFG_READ_UR_MODE, SCB_ACCESS_EN,
- * RCB_MPS_MODE, RCB_64B_MODE
+ * RCB_MPS_MODE
*/
tmp = readl(base + PCIE_MISC_MISC_CTRL);
u32p_replace_bits(&tmp, 1, PCIE_MISC_MISC_CTRL_SCB_ACCESS_EN_MASK);
u32p_replace_bits(&tmp, 1, PCIE_MISC_MISC_CTRL_CFG_READ_UR_MODE_MASK);
u32p_replace_bits(&tmp, burst, PCIE_MISC_MISC_CTRL_MAX_BURST_SIZE_MASK);
- u32p_replace_bits(&tmp, 1, PCIE_MISC_MISC_CTRL_PCIE_RCB_MPS_MODE_MASK);
- u32p_replace_bits(&tmp, 1, PCIE_MISC_MISC_CTRL_PCIE_RCB_64B_MODE_MASK);
+ if (pcie->rcb_mps_mode)
+ u32p_replace_bits(&tmp, 1, PCIE_MISC_MISC_CTRL_PCIE_RCB_MPS_MODE_MASK);
writel(tmp, base + PCIE_MISC_MISC_CTRL);
brcm_pcie_set_tc_qos(pcie);
@@ -1917,6 +1918,7 @@ static int brcm_pcie_probe(struct platfo
pcie->ssc = of_property_read_bool(np, "brcm,enable-ssc");
pcie->l1ss = of_property_read_bool(np, "brcm,enable-l1ss");
+ pcie->rcb_mps_mode = of_property_read_bool(np, "brcm,enable-mps-rcb");
ret = clk_prepare_enable(pcie->clk);
if (ret) {