Not doing this might waste bus bandwidth or even cause memory corruption or
system crashes on systems that check bus transfers. No such incident has been
reported though.
dev_priv->writeback_works = 0;
DRM_INFO("writeback forced off\n");
}
+
+ if (!dev_priv->writeback_works) {
+ /* Disable writeback to avoid unnecessary bus master transfers */
+ RADEON_WRITE(RADEON_CP_RB_CNTL, RADEON_READ(RADEON_CP_RB_CNTL) | RADEON_RB_NO_UPDATE);
+ RADEON_WRITE(RADEON_SCRATCH_UMSK, 0);
+ }
}
/* Enable or disable PCI-E GART on the chip */
#define RADEON_CP_RB_BASE 0x0700
#define RADEON_CP_RB_CNTL 0x0704
# define RADEON_BUF_SWAP_32BIT (2 << 16)
+# define RADEON_RB_NO_UPDATE (1 << 27)
#define RADEON_CP_RB_RPTR_ADDR 0x070c
#define RADEON_CP_RB_RPTR 0x0710
#define RADEON_CP_RB_WPTR 0x0714