[PATCH 5.13 188/266] drm/amdgpu: fix NAK-G generation during PCI-e link width switch

Greg Kroah-Hartman
2021-07-15T19:40:59Z

From: Evan Quan <evan.quan@amd.com>

commit 5a5da8ae9546031e43efd4fa5aa8baa481e83dfb upstream.

A lot of NAK-G being generated when link widht switching is happening.
WA for this issue is to program the SPC to 4 symbols per clock during
bootup when the native PCIE width is x4.

Signed-off-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/gpu/drm/amd/amdgpu/amdgpu_nbio.h | 1 +
drivers/gpu/drm/amd/amdgpu/nbio_v2_3.c | 28 ++++++++++++++++++++++++++++
drivers/gpu/drm/amd/amdgpu/nv.c | 3 +++
3 files changed, 32 insertions(+)

--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_nbio.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_nbio.h
@@ -93,6 +93,7 @@ struct amdgpu_nbio_funcs {
void (*enable_aspm)(struct amdgpu_device *adev,
bool enable);
void (*program_aspm)(struct amdgpu_device *adev);
+ void (*apply_lc_spc_mode_wa)(struct amdgpu_device *adev);
};

struct amdgpu_nbio {
--- a/drivers/gpu/drm/amd/amdgpu/nbio_v2_3.c
+++ b/drivers/gpu/drm/amd/amdgpu/nbio_v2_3.c
@@ -51,6 +51,8 @@
#define mmBIF_MMSCH1_DOORBELL_RANGE 0x01d8
#define mmBIF_MMSCH1_DOORBELL_RANGE_BASE_IDX 2

+#define smnPCIE_LC_LINK_WIDTH_CNTL 0x11140288
+
static void nbio_v2_3_remap_hdp_registers(struct amdgpu_device *adev)
{
WREG32_SOC15(NBIO, 0, mmREMAP_HDP_MEM_FLUSH_CNTL,
@@ -463,6 +465,31 @@ static void nbio_v2_3_program_aspm(struc
WREG32_PCIE(smnPCIE_LC_CNTL3, data);
}

+static void nbio_v2_3_apply_lc_spc_mode_wa(struct amdgpu_device *adev)
+{
+ uint32_t reg_data = 0;
+ uint32_t link_width = 0;
+
+ if (!((adev->asic_type >= CHIP_NAVI10) &&
+ (adev->asic_type <= CHIP_NAVI12)))
+ return;
+
+ reg_data = RREG32_PCIE(smnPCIE_LC_LINK_WIDTH_CNTL);
+ link_width = (reg_data & PCIE_LC_LINK_WIDTH_CNTL__LC_LINK_WIDTH_RD_MASK)
+ >> PCIE_LC_LINK_WIDTH_CNTL__LC_LINK_WIDTH_RD__SHIFT;
+
+ /*
+ * Program PCIE_LC_CNTL6.LC_SPC_MODE_8GT to 0x2 (4 symbols per clock data)
+ * if link_width is 0x3 (x4)
+ */
+ if (0x3 == link_width) {
+ reg_data = RREG32_PCIE(smnPCIE_LC_CNTL6);
+ reg_data &= ~PCIE_LC_CNTL6__LC_SPC_MODE_8GT_MASK;
+ reg_data |= (0x2 << PCIE_LC_CNTL6__LC_SPC_MODE_8GT__SHIFT);
+ WREG32_PCIE(smnPCIE_LC_CNTL6, reg_data);
+ }
+}
+
const struct amdgpu_nbio_funcs nbio_v2_3_funcs = {
.get_hdp_flush_req_offset = nbio_v2_3_get_hdp_flush_req_offset,
.get_hdp_flush_done_offset = nbio_v2_3_get_hdp_flush_done_offset,
@@ -484,4 +511,5 @@ const struct amdgpu_nbio_funcs nbio_v2_3
.remap_hdp_registers = nbio_v2_3_remap_hdp_registers,
.enable_aspm = nbio_v2_3_enable_aspm,
.program_aspm = nbio_v2_3_program_aspm,
+ .apply_lc_spc_mode_wa = nbio_v2_3_apply_lc_spc_mode_wa,
};
--- a/drivers/gpu/drm/amd/amdgpu/nv.c
+++ b/drivers/gpu/drm/amd/amdgpu/nv.c
@@ -1194,6 +1194,9 @@ static int nv_common_hw_init(void *handl
{
struct amdgpu_device *adev = (struct amdgpu_device *)handle;

+ if (adev->nbio.funcs->apply_lc_spc_mode_wa)
+ adev->nbio.funcs->apply_lc_spc_mode_wa(adev);
+
/* enable pcie gen2/3 link */
nv_pcie_gen3_enable(adev);
/* enable aspm */