Patchwork [v4,3/3] PCI: imx6: limit DBI register length

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Submitter Stefan Agner
Date Dec. 4, 2018, 4:55 p.m.
Message ID <20181204165528.15534-3-stefan@agner.ch>
Download mbox | patch
Permalink /patch/672209/
State New
Headers show

Comments

Stefan Agner - Dec. 4, 2018, 4:55 p.m.
Define the length of the DBI registers. This makes sure that
the kernel does not access registers beyond that point, avoiding
the following abort on a i.MX 6Quad:
  # cat /sys/devices/soc0/soc/1ffc000.pcie/pci0000\:00/0000\:00\:00.0/config
  [  100.021433] Unhandled fault: imprecise external abort (0x1406) at 0xb6ea7000
  ...
  [  100.056423] PC is at dw_pcie_read+0x50/0x84
  [  100.060790] LR is at dw_pcie_rd_own_conf+0x44/0x48
  ...

Signed-off-by: Stefan Agner <stefan@agner.ch>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
---
Changes in v3:
- Rebase on pci/dwc
Changes in v4:
- Rebase on pci/dwc

 drivers/pci/controller/dwc/pci-imx6.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
Leonard Crestez - Dec. 4, 2018, 7:08 p.m.
On Tue, 2018-12-04 at 17:55 +0100, Stefan Agner wrote:
> Define the length of the DBI registers. This makes sure that

> the kernel does not access registers beyond that point, avoiding

> the following abort on a i.MX 6Quad:

>   # cat /sys/devices/soc0/soc/1ffc000.pcie/pci0000\:00/0000\:00\:00.0/config

>   [  100.021433] Unhandled fault: imprecise external abort (0x1406) at 0xb6ea7000

>   ...

>   [  100.056423] PC is at dw_pcie_read+0x50/0x84

>   [  100.060790] LR is at dw_pcie_rd_own_conf+0x44/0x48

> 

>  static const struct imx6_pcie_drvdata drvdata[] = {

> -	[IMX6Q] = { .variant = IMX6Q },

> +	[IMX6Q] = { .variant = IMX6Q, .dbi_length = 0x15c },

>  	[IMX6SX] = { .variant = IMX6SX },

>  	[IMX6QP] = { .variant = IMX6QP },

>  	[IMX7D] = { .variant = IMX7D },


Also seems to affect IMX6QP variant (but not others).

Lucas suggested 0x15c because that's the last register documented in
the datasheet but the real HW limit is 0x200, wouldn't it make more
sense to use that?

--
Regards,
Leonard

Patch

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index 45cbdf2ccf80..a69eb625ed18 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -43,6 +43,7 @@  enum imx6_pcie_variants {
 
 struct imx6_pcie_drvdata {
 	enum imx6_pcie_variants variant;
+	int			dbi_length;
 };
 
 struct imx6_pcie {
@@ -1015,6 +1016,8 @@  static int imx6_pcie_probe(struct platform_device *pdev)
 		break;
 	}
 
+	pci->dbi_length = imx6_pcie->drvdata->dbi_length;
+
 	/* Grab turnoff reset */
 	imx6_pcie->turnoff_reset = devm_reset_control_get_optional_exclusive(dev, "turnoff");
 	if (IS_ERR(imx6_pcie->turnoff_reset)) {
@@ -1086,7 +1089,7 @@  static void imx6_pcie_shutdown(struct platform_device *pdev)
 }
 
 static const struct imx6_pcie_drvdata drvdata[] = {
-	[IMX6Q] = { .variant = IMX6Q },
+	[IMX6Q] = { .variant = IMX6Q, .dbi_length = 0x15c },
 	[IMX6SX] = { .variant = IMX6SX },
 	[IMX6QP] = { .variant = IMX6QP },
 	[IMX7D] = { .variant = IMX7D },