[PATCH] drm/radeon: Add error handlings for r420 CP errata initialization

[Wentao Liang]

In r420_cp_errata_init(), the RESYNC information is stored even
when the Scratch register is not correctly allocated.

Change the return type of r420_cp_errata_init() from void to int
to propagate errors to the caller. Add error checking after
radeon_scratch_get() to ensure RESYNC information is stored
to an allocated address. Log an error message and return the
error code immediately when radeon_scratch_get() fails.
Additionally, handle the return value of r420_cp_errata_init() in
r420_startup() to log an appropriate error message and propagate
the error if initialization fails.

Fixes: 62cdc0c20663 ("drm/radeon/kms: Workaround RV410/R420 CP errata (V3)")

Cc: sta...@vger.kernel.org # 2.6.33+
Signed-off-by: Wentao Liang <vu...@iscas.ac.cn>
---
 drivers/gpu/drm/radeon/r420.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/radeon/r420.c b/drivers/gpu/drm/radeon/r420.c
index 9a31cdec6415..67c55153cba8 100644
--- a/drivers/gpu/drm/radeon/r420.c
+++ b/drivers/gpu/drm/radeon/r420.c
@@ -204,7 +204,7 @@ static void r420_clock_resume(struct radeon_device *rdev)
        WREG32_PLL(R_00000D_SCLK_CNTL, sclk_cntl);
 }
 
-static void r420_cp_errata_init(struct radeon_device *rdev)
+static int r420_cp_errata_init(struct radeon_device *rdev)
 {
        int r;
        struct radeon_ring *ring = &rdev->ring[RADEON_RING_TYPE_GFX_INDEX];
@@ -215,7 +215,11 @@ static void r420_cp_errata_init(struct radeon_device *rdev)
         * The proper workaround is to queue a RESYNC at the beginning
         * of the CP init, apparently.
         */
-       radeon_scratch_get(rdev, &rdev->config.r300.resync_scratch);
+       r = radeon_scratch_get(rdev, &rdev->config.r300.resync_scratch);
+       if (r) {
+               DRM_ERROR("failed to get scratch reg (%d).\n", r);
+               return r;
+       }
        r = radeon_ring_lock(rdev, ring, 8);
        WARN_ON(r);
        radeon_ring_write(ring, PACKET0(R300_CP_RESYNC_ADDR, 1));
@@ -290,8 +294,11 @@ static int r420_startup(struct radeon_device *rdev)
                dev_err(rdev->dev, "failed initializing CP (%d).\n", r);
                return r;
        }
-       r420_cp_errata_init(rdev);
-
+       r = r420_cp_errata_init(rdev);
+       if (r) {
+               dev_err(rdev->dev, "failed initializing CP errata workaround 
(%d).\n", r);
+               return r;
+       }
        r = radeon_ib_pool_init(rdev);
        if (r) {
                dev_err(rdev->dev, "IB initialization failed (%d).\n", r);
-- 
2.42.0.windows.2