On 8/12/24 18:28, Stanimir Varbanov wrote:

Hi Jim,

On 8/12/24 18:46, Jim Quinlan wrote:

quoted

On Fri, Aug 9, 2024 at 7:16 AM Stanimir Varbanov [off-list ref] wrote:

quoted

Hi Jim,

On 8/1/24 01:28, Jim Quinlan wrote:

quoted

The 7712 SOC has a bridge reset which can be described in the device tree.
Use it if present.  Otherwise, continue to use the legacy method to reset
the bridge.

Signed-off-by: Jim Quinlan <redacted>
---
  drivers/pci/controller/pcie-brcmstb.c | 24 +++++++++++++++++++-----
  1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
index 7595e7009192..4d68fe318178 100644
--- a/drivers/pci/controller/pcie-brcmstb.c
+++ b/drivers/pci/controller/pcie-brcmstb.c

@@ -265,6 +265,7 @@ struct brcm_pcie {
       enum pcie_type          type;
       struct reset_control    *rescal;
       struct reset_control    *perst_reset;
+     struct reset_control    *bridge_reset;
       int                     num_memc;
       u64                     memc_size[PCIE_BRCM_MAX_MEMC];
       u32                     hw_rev;

@@ -732,12 +733,19 @@ static void __iomem *brcm7425_pcie_map_bus(struct pci_bus *bus,

  static void brcm_pcie_bridge_sw_init_set_generic(struct brcm_pcie *pcie, u32 val)
  {
-     u32 tmp, mask =  RGR1_SW_INIT_1_INIT_GENERIC_MASK;
-     u32 shift = RGR1_SW_INIT_1_INIT_GENERIC_SHIFT;
+     if (val)
+             reset_control_assert(pcie->bridge_reset);
+     else
+             reset_control_deassert(pcie->bridge_reset);

-     tmp = readl(pcie->base + PCIE_RGR1_SW_INIT_1(pcie));
-     tmp = (tmp & ~mask) | ((val << shift) & mask);
-     writel(tmp, pcie->base + PCIE_RGR1_SW_INIT_1(pcie));
+     if (!pcie->bridge_reset) {
+             u32 tmp, mask =  RGR1_SW_INIT_1_INIT_GENERIC_MASK;
+             u32 shift = RGR1_SW_INIT_1_INIT_GENERIC_SHIFT;
+
+             tmp = readl(pcie->base + PCIE_RGR1_SW_INIT_1(pcie));
+             tmp = (tmp & ~mask) | ((val << shift) & mask);
+             writel(tmp, pcie->base + PCIE_RGR1_SW_INIT_1(pcie));
+     }
  }

  static void brcm_pcie_bridge_sw_init_set_7278(struct brcm_pcie *pcie, u32 val)

@@ -1621,10 +1629,16 @@ static int brcm_pcie_probe(struct platform_device *pdev)
       if (IS_ERR(pcie->perst_reset))
               return PTR_ERR(pcie->perst_reset);

+     pcie->bridge_reset = devm_reset_control_get_optional_exclusive(&pdev->dev, "bridge");

Shouldn't this be devm_reset_control_get_optional_shared? See more below.

quoted

+     if (IS_ERR(pcie->bridge_reset))
+             return PTR_ERR(pcie->bridge_reset);
+
       ret = clk_prepare_enable(pcie->clk);
       if (ret)
               return dev_err_probe(&pdev->dev, ret, "could not enable clock\n");

+     pcie->bridge_sw_init_set(pcie, 0);

^^^ this was missing in v4

Hi Stan,

You are correct and I was remiss in not mentioning this in the cover 
letter.  After my changes on V4 I discovered that my driver failed the 
rebind in my unbind/rebind test and this line was required.

quoted

quoted

According to reset_control_get_shared description looks like this
.deassert is satisfying the requirements for _shared reset-control API
variant.
Is that the intention to call reset_control_deassert() here?

Hi Stan,
Now I'm not sure I understand you.  All of the resets (bridge, perst,
swinit) are exclusive, except for the "rescal" reset, which is shared.

... the call of pcie->bridge_sw_init_set(pcie, 0) from brcm_pcie_probe()
was missing in previous v4 and I'm wondering what changed in v5.

And because of _shared reset-control description [1] I decided (wrongly)
that the bridge reset could be _shared_.

quoted

On the exclusive resets I am using reset_control_assert() and
reset_control_deasssert().  On the shared reset I am using
reset_control_rearm() and reset_control_reset().   Why do
you think the calls I am using are incongruent with the shard/exclusive
status?

I'd argue that rescal reset is not correctly used in brcm_pcie_probe(),
see [2] and according to [1] "Calling reset_control_reset is also not
allowed on a shared reset control."

This is interesting because in reset/core.c [1]  the comment says that 
"reset_control_rearm", which is clearly used for shared resets, must be 
paired with calls to "reset_control_reset".

Regards,

Jim Quinlan

Broadcom STB/CM

[1] 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/reset/core.c?h=v6.11-rc3#n412

[1]
https://elixir.bootlin.com/linux/v6.11-rc3/source/include/linux/reset.h#L338

[2]
https://elixir.bootlin.com/linux/v6.11-rc3/source/drivers/pci/controller/pcie-brcmstb.c#L1632

~Stan