Hi Xiaojie,
could you add that test to the unit tests we have in libdrm?
Would be rather nice to have,
Christian.
Am 18.11.19 um 15:09 schrieb Yuan, Xiaojie:
Hi Alex,
I tried on Navi14 with Gfxoff enabled (gfx in 'OFF' state when I run the test
program) and used a test program to read GRBM_STATUS/CP_STAT/GB_ADDR_CONFIG via
DRM_IOCTL_AMDGPU_INFO.
All read out values are valid as below (in this read cycle, I saw gfx block is
first awakened and then powered off again automatically):
drm version: 3.36.0
grbm_status: 0x00003028
cp_stat: 0x00000000
gb_addr_config: 0x00000043
At least for Navi, reading register when gfxoff seems not a problem...
Test program:
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <errno.h>
#include <libdrm/drm.h>
#include <libdrm/amdgpu_drm.h>
int get_reg_val(int fd, int reg_offset, int *val)
{
struct drm_amdgpu_info request;
int r;
memset(&request, 0, sizeof(request));
request.return_pointer = (uintptr_t)val;
request.return_size = sizeof(uint32_t);
request.query = AMDGPU_INFO_READ_MMR_REG;
request.read_mmr_reg.dword_offset = reg_offset;
request.read_mmr_reg.count = 1;
request.read_mmr_reg.instance = 0xffffffff;
request.read_mmr_reg.flags = 0;
r = ioctl(fd, DRM_IOCTL_AMDGPU_INFO, &request);
if (r < 0) {
perror("failed to read register");
return -errno;
}
return 0;
}
int main(int argc, const char *argv[])
{
const char *device = "/dev/dri/card0";
int fd;
int r;
struct drm_version version;
struct drm_auth auth;
int cp_stat;
int grbm_status;
int gb_addr_config;
fd = open(device, O_RDWR | O_CLOEXEC);
if (fd < 0) {
perror("failed to open device\n");
return -errno;
}
memset(&version, 0, sizeof(version));
r = ioctl(fd, DRM_IOCTL_VERSION, &version);
if (r < 0) {
perror("failed to get drm version");
r = -errno;
goto close;
}
printf("drm version: %d.%d.%d\n", version.version_major,
version.version_minor,
version.version_patchlevel);
r = get_reg_val(fd, 0x2004, &grbm_status);
if (r < 0)
goto close;
printf("grbm_status: 0x%08x\n", grbm_status);
r = get_reg_val(fd, 0x21a0, &cp_stat);
if (r < 0)
goto close;
printf("cp_stat: 0x%08x\n", cp_stat);
r = get_reg_val(fd, 0x263e, &gb_addr_config);
if (r < 0)
goto close;
printf("gb_addr_config: 0x%08x\n", gb_addr_config);
close:
close(fd);
return r;
}
BR,
Xiaojie
________________________________________
From: amd-gfx <[email protected]> on behalf of Yuan, Xiaojie
<[email protected]>
Sent: Saturday, November 16, 2019 1:02 AM
To: Alex Deucher
Cc: Deucher, Alexander; [email protected]
Subject: Re: [PATCH 2/2] drm/amdgpu: disable gfxoff when using register read
interface
Yes. IIRC, some asics' amdgpu_gfx_ctrl() is implemented as synchronous (upon
function returns, gfx block is guaranteed to be in power-up state). Anyway, let
me confirm about that soon.
BR,
Xiaojie
On Nov 16, 2019, at 12:52 AM, Alex Deucher <[email protected]> wrote:
On Fri, Nov 15, 2019 at 11:46 AM Yuan, Xiaojie <[email protected]> wrote:
Hi Alex,
IMHO, driver sending Disallow_Gfxoff message to SMU doesn't mean gfx block will
be immediately powered up, so I'm not sure MMIO register access will be
successful within this time window(maybe GRBM access will be pending until gfx
block is powered up?)
If you are not in a hurry to commit this fix, I can verify on my Navi boards
next Monday.
That would be great. Maybe we can add a delay in that function to
take that into account?
Thanks!
Alex
BR,
Xiaojie
On Nov 15, 2019, at 12:44 AM, Alex Deucher <[email protected]> wrote:
When gfxoff is enabled, accessing gfx registers via MMIO
can lead to a hang.
Bug: https://bugzilla.kernel.org/show_bug.cgi?id=205497
Signed-off-by: Alex Deucher <[email protected]>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
index 6ddea7607ad0..5f3b3a705b29 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
@@ -659,15 +659,19 @@ static int amdgpu_info_ioctl(struct drm_device *dev, void
*data, struct drm_file
return -ENOMEM;
alloc_size = info->read_mmr_reg.count * sizeof(*regs);
- for (i = 0; i < info->read_mmr_reg.count; i++)
+ amdgpu_gfx_off_ctrl(adev, false);
+ for (i = 0; i < info->read_mmr_reg.count; i++) {
if (amdgpu_asic_read_register(adev, se_num, sh_num,
info->read_mmr_reg.dword_offset + i,
®s[i])) {
DRM_DEBUG_KMS("unallowed offset %#x\n",
info->read_mmr_reg.dword_offset + i);
kfree(regs);
+ amdgpu_gfx_off_ctrl(adev, true);
return -EFAULT;
}
+ }
+ amdgpu_gfx_off_ctrl(adev, true);
n = copy_to_user(out, regs, min(size, alloc_size));
kfree(regs);
return n ? -EFAULT : 0;
--
2.23.0
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