[PATCH] drm/amdgpu: initialize iter.start in amdgpu_devcoredump_format

[Qiang Yu]

From: Qiang Yu <qiang...@amd.com>

This fixes read /sys/class/drm/cardN/device/devcoredump/data
return empty content sometimes.

amdgpu_devcoredump_format() leaves struct drm_print_iterator's
.start field uninitialized on the stack before passing it to
drm_coredump_printer(). __drm_puts_coredump() compares the running
.offset against .start to decide whether to skip or copy each
chunk:

        if (iterator->offset < iterator->start) {
                if (iterator->offset + len <= iterator->start) {
                        iterator->offset += len;
                        return;
                }
                ...
        }

Fixes: 4f28b4930f8e ("drm/amdgpu: move devcoredump generation to a worker")
Signed-off-by: Qiang Yu <qiang...@amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_dev_coredump.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_dev_coredump.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_dev_coredump.c
index 46043a1479e4..63d7ef78c025 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_dev_coredump.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_dev_coredump.c
@@ -219,6 +219,7 @@ amdgpu_devcoredump_format(char *buffer, size_t count, 
struct amdgpu_coredump_inf
        u32 ring_idx, off;
 
        iter.data = buffer;
+       iter.start = 0;
        iter.offset = 0;
        iter.remain = count;
 
-- 
2.43.0