path: root/drivers/gpu/ipu-v3/ipu-pre.c
diff options
authorLucas Stach <>2018-12-18 16:46:29 +0100
committerPhilipp Zabel <>2019-01-23 11:56:44 +0100
commiteb0200a4357da100064971689d3a0e9e3cf57f33 (patch)
tree4e0f5db916c737339c2e5a911c06b1873570722b /drivers/gpu/ipu-v3/ipu-pre.c
parentbb867d219fda7fbaabea3314702474c4eac2b91d (diff)
gpu: ipu-v3: pre: don't trigger update if buffer address doesn't change
On a NOP double buffer update where current buffer address is the same as the next buffer address, the SDW_UPDATE bit clears too late. As we are now using this bit to determine when it is safe to signal flip completion to userspace this will delay completion of atomic commits where one plane doesn't change the buffer by a whole frame period. Fix this by remembering the last buffer address and just skip the double buffer update if it would not change the buffer address. Signed-off-by: Lucas Stach <> [ initialize last_bufaddr in ipu_pre_configure] Signed-off-by: Philipp Zabel <>
Diffstat (limited to 'drivers/gpu/ipu-v3/ipu-pre.c')
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/gpu/ipu-v3/ipu-pre.c b/drivers/gpu/ipu-v3/ipu-pre.c
index 2f8db9d62551..4a28f3fbb0a2 100644
--- a/drivers/gpu/ipu-v3/ipu-pre.c
+++ b/drivers/gpu/ipu-v3/ipu-pre.c
@@ -106,6 +106,7 @@ struct ipu_pre {
void *buffer_virt;
bool in_use;
unsigned int safe_window_end;
+ unsigned int last_bufaddr;
static DEFINE_MUTEX(ipu_pre_list_mutex);
@@ -185,6 +186,7 @@ void ipu_pre_configure(struct ipu_pre *pre, unsigned int width,
writel(bufaddr, pre->regs + IPU_PRE_CUR_BUF);
writel(bufaddr, pre->regs + IPU_PRE_NEXT_BUF);
+ pre->last_bufaddr = bufaddr;
@@ -242,7 +244,11 @@ void ipu_pre_update(struct ipu_pre *pre, unsigned int bufaddr)
unsigned short current_yblock;
u32 val;
+ if (bufaddr == pre->last_bufaddr)
+ return;
writel(bufaddr, pre->regs + IPU_PRE_NEXT_BUF);
+ pre->last_bufaddr = bufaddr;
do {
if (time_after(jiffies, timeout)) {