[PATCH] PCI: meson: Remove meson_pcie_link_up() timeout, message, speed check

[PATCH] PCI: meson: Remove meson_pcie_link_up() timeout, message, speed check

[Bjorn Helgaas]

From: Bjorn Helgaas <bhelgaas@google.com>

Previously meson_pcie_link_up() only returned true if the link was in the
L0 state.  This was incorrect because hardware autonomously manages
transitions between L0, L0s, and L1 while both components on the link stay
in D0.  Those states should all be treated as "link is active".

Returning false when the device was in L0s or L1 broke config accesses
because dw_pcie_other_conf_map_bus() fails if the link is down, which
caused errors like this:

  meson-pcie fc000000.pcie: error: wait linkup timeout
  pci 0000:01:00.0: BAR 0: error updating (0xfc700004 != 0xffffffff)

Remove the LTSSM state check, timeout, speed check, and error message from
meson_pcie_link_up(), the dw_pcie_ops.link_up() method, so it is a simple
boolean check of whether the link is active.  Timeouts and and error
messages are handled at a higher level, e.g., dw_pcie_wait_for_link().

Fixes: 9c0ef6d34fdb ("PCI: amlogic: Add the Amlogic Meson PCIe controller driver")
Reported-by: Linnaea Lavia <linnaea-von-lavia@live.com>
Closes: https://lore.kernel.org/r/DM4PR05MB102707B8CDF84D776C39F22F2C7F0A@DM4PR05MB10270.namprd05.prod.outlook.com
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Linnaea Lavia <linnaea-von-lavia@live.com>
Cc: stable@vger.kernel.org
---
 drivers/pci/controller/dwc/pci-meson.c | 36 +++-----------------------
 1 file changed, 3 insertions(+), 33 deletions(-)

diff --git a/drivers/pci/controller/dwc/pci-meson.c b/drivers/pci/controller/dwc/pci-meson.c
index 787469d1b396..13685d89227a 100644
--- a/drivers/pci/controller/dwc/pci-meson.c
+++ b/drivers/pci/controller/dwc/pci-meson.c
@@ -338,40 +338,10 @@ static struct pci_ops meson_pci_ops = {
 static bool meson_pcie_link_up(struct dw_pcie *pci)
 {
 	struct meson_pcie *mp = to_meson_pcie(pci);
-	struct device *dev = pci->dev;
-	u32 speed_okay = 0;
-	u32 cnt = 0;
-	u32 state12, state17, smlh_up, ltssm_up, rdlh_up;
+	u32 state12;
 
-	do {
-		state12 = meson_cfg_readl(mp, PCIE_CFG_STATUS12);
-		state17 = meson_cfg_readl(mp, PCIE_CFG_STATUS17);
-		smlh_up = IS_SMLH_LINK_UP(state12);
-		rdlh_up = IS_RDLH_LINK_UP(state12);
-		ltssm_up = IS_LTSSM_UP(state12);
-
-		if (PM_CURRENT_STATE(state17) < PCIE_GEN3)
-			speed_okay = 1;
-
-		if (smlh_up)
-			dev_dbg(dev, "smlh_link_up is on\n");
-		if (rdlh_up)
-			dev_dbg(dev, "rdlh_link_up is on\n");
-		if (ltssm_up)
-			dev_dbg(dev, "ltssm_up is on\n");
-		if (speed_okay)
-			dev_dbg(dev, "speed_okay\n");
-
-		if (smlh_up && rdlh_up && ltssm_up && speed_okay)
-			return true;
-
-		cnt++;
-
-		udelay(10);
-	} while (cnt < WAIT_LINKUP_TIMEOUT);
-
-	dev_err(dev, "error: wait linkup timeout\n");
-	return false;
+	state12 = meson_cfg_readl(mp, PCIE_CFG_STATUS12);
+	return IS_SMLH_LINK_UP(state12) && IS_RDLH_LINK_UP(state12);
 }
 
 static int meson_pcie_host_init(struct dw_pcie_rp *pp)
-- 
2.43.0

Re: [PATCH] PCI: meson: Remove meson_pcie_link_up() timeout, message, speed check

[Neil Armstrong]

On 11/3/25 23:19, Bjorn Helgaas wrote:
> From: Bjorn Helgaas <bhelgaas@google.com>
> 
> Previously meson_pcie_link_up() only returned true if the link was in the
> L0 state.  This was incorrect because hardware autonomously manages
> transitions between L0, L0s, and L1 while both components on the link stay
> in D0.  Those states should all be treated as "link is active".
> 
> Returning false when the device was in L0s or L1 broke config accesses
> because dw_pcie_other_conf_map_bus() fails if the link is down, which
> caused errors like this:
> 
>    meson-pcie fc000000.pcie: error: wait linkup timeout
>    pci 0000:01:00.0: BAR 0: error updating (0xfc700004 != 0xffffffff)
> 
> Remove the LTSSM state check, timeout, speed check, and error message from
> meson_pcie_link_up(), the dw_pcie_ops.link_up() method, so it is a simple
> boolean check of whether the link is active.  Timeouts and and error
> messages are handled at a higher level, e.g., dw_pcie_wait_for_link().
> 
> Fixes: 9c0ef6d34fdb ("PCI: amlogic: Add the Amlogic Meson PCIe controller driver")
> Reported-by: Linnaea Lavia <linnaea-von-lavia@live.com>
> Closes: https://lore.kernel.org/r/DM4PR05MB102707B8CDF84D776C39F22F2C7F0A@DM4PR05MB10270.namprd05.prod.outlook.com
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> Tested-by: Linnaea Lavia <linnaea-von-lavia@live.com>
> Cc: stable@vger.kernel.org
> ---
>   drivers/pci/controller/dwc/pci-meson.c | 36 +++-----------------------
>   1 file changed, 3 insertions(+), 33 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pci-meson.c b/drivers/pci/controller/dwc/pci-meson.c
> index 787469d1b396..13685d89227a 100644
> --- a/drivers/pci/controller/dwc/pci-meson.c
> +++ b/drivers/pci/controller/dwc/pci-meson.c
> @@ -338,40 +338,10 @@ static struct pci_ops meson_pci_ops = {
>   static bool meson_pcie_link_up(struct dw_pcie *pci)
>   {
>   	struct meson_pcie *mp = to_meson_pcie(pci);
> -	struct device *dev = pci->dev;
> -	u32 speed_okay = 0;
> -	u32 cnt = 0;
> -	u32 state12, state17, smlh_up, ltssm_up, rdlh_up;
> +	u32 state12;
>   
> -	do {
> -		state12 = meson_cfg_readl(mp, PCIE_CFG_STATUS12);
> -		state17 = meson_cfg_readl(mp, PCIE_CFG_STATUS17);
> -		smlh_up = IS_SMLH_LINK_UP(state12);
> -		rdlh_up = IS_RDLH_LINK_UP(state12);
> -		ltssm_up = IS_LTSSM_UP(state12);
> -
> -		if (PM_CURRENT_STATE(state17) < PCIE_GEN3)
> -			speed_okay = 1;
> -
> -		if (smlh_up)
> -			dev_dbg(dev, "smlh_link_up is on\n");
> -		if (rdlh_up)
> -			dev_dbg(dev, "rdlh_link_up is on\n");
> -		if (ltssm_up)
> -			dev_dbg(dev, "ltssm_up is on\n");
> -		if (speed_okay)
> -			dev_dbg(dev, "speed_okay\n");
> -
> -		if (smlh_up && rdlh_up && ltssm_up && speed_okay)
> -			return true;
> -
> -		cnt++;
> -
> -		udelay(10);
> -	} while (cnt < WAIT_LINKUP_TIMEOUT);
> -
> -	dev_err(dev, "error: wait linkup timeout\n");
> -	return false;
> +	state12 = meson_cfg_readl(mp, PCIE_CFG_STATUS12);
> +	return IS_SMLH_LINK_UP(state12) && IS_RDLH_LINK_UP(state12);
>   }
>   
>   static int meson_pcie_host_init(struct dw_pcie_rp *pp)

Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on BananaPi M2S

Thanks !

Neil