The SOC_HW_VERSION register in the BHI space is not correctly initialized
by the device and in many cases contains uninitialized data. The register
could contain 0xFFFFFFFF which is a special value to indicate a link
error in PCIe, therefore if observed, we could incorrectly think the
device is down.
Intercept reads for this register, and provide the correct value - every
production instance would read 0x60110200 if the device was operating as
intended.
Fixes: a36bf7af868b ("accel/qaic: Add MHI controller")
Signed-off-by: Jeffrey Hugo <quic_jhugo@xxxxxxxxxxx>
Reviewed-by: Pranjal Ramajor Asha Kanojiya <quic_pkanojiy@xxxxxxxxxxx>
---
drivers/accel/qaic/mhi_controller.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)
diff --git a/drivers/accel/qaic/mhi_controller.c b/drivers/accel/qaic/mhi_controller.c
index 5036e58e7235..1405623b03e4 100644
--- a/drivers/accel/qaic/mhi_controller.c
+++ b/drivers/accel/qaic/mhi_controller.c
@@ -404,8 +404,21 @@ static struct mhi_controller_config aic100_config = {
static int mhi_read_reg(struct mhi_controller *mhi_cntrl, void __iomem *addr, u32 *out)
{
- u32 tmp = readl_relaxed(addr);
+ u32 tmp;
+ /*
+ * SOC_HW_VERSION quirk
+ * The SOC_HW_VERSION register (offset 0x224) is not reliable and
+ * may contain uninitialized values, including 0xFFFFFFFF. This could
+ * cause a false positive link down error. Instead, intercept any
+ * reads and provide the correct value of the register.
+ */
+ if (addr - mhi_cntrl->regs == 0x224) {
+ *out = 0x60110200;
+ return 0;
+ }
+
+ tmp = readl_relaxed(addr);
if (tmp == U32_MAX)
return -EIO;
--
2.34.1
