From: Lucas Stach l.stach@pengutronix.de

The PRE has a bug where a software write to the CTRL register can block the setting of the ENABLE bit by the hardware in auto repeat mode. When this happens the PRE will fail to handle new jobs. To work around this software must not write to CTRL register when the PRE store engine is inside the unsafe window, where a hardware update to the ENABLE bit may happen.

Signed-off-by: Lucas Stach l.stach@pengutronix.de [p.zabel@pengutronix.de: rebased before PRE tiled prefetch support] Signed-off-by: Philipp Zabel p.zabel@pengutronix.de --- drivers/gpu/ipu-v3/ipu-pre.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+)

diff --git a/drivers/gpu/ipu-v3/ipu-pre.c b/drivers/gpu/ipu-v3/ipu-pre.c index c35f74c830657..c860a7997cb59 100644 --- a/drivers/gpu/ipu-v3/ipu-pre.c +++ b/drivers/gpu/ipu-v3/ipu-pre.c @@ -73,6 +73,14 @@ #define IPU_PRE_STORE_ENG_CTRL_WR_NUM_BYTES(v) ((v & 0x7) << 1) #define IPU_PRE_STORE_ENG_CTRL_OUTPUT_ACTIVE_BPP(v) ((v & 0x3) << 4)

+#define IPU_PRE_STORE_ENG_STATUS 0x120 +#define IPU_PRE_STORE_ENG_STATUS_STORE_BLOCK_X_MASK 0xffff +#define IPU_PRE_STORE_ENG_STATUS_STORE_BLOCK_X_SHIFT 0 +#define IPU_PRE_STORE_ENG_STATUS_STORE_BLOCK_Y_MASK 0x3fff +#define IPU_PRE_STORE_ENG_STATUS_STORE_BLOCK_Y_SHIFT 16 +#define IPU_PRE_STORE_ENG_STATUS_STORE_FIFO_FULL (1 << 30) +#define IPU_PRE_STORE_ENG_STATUS_STORE_FIELD (1 << 31) + #define IPU_PRE_STORE_ENG_SIZE 0x130 #define IPU_PRE_STORE_ENG_SIZE_INPUT_WIDTH(v) ((v & 0xffff) << 0) #define IPU_PRE_STORE_ENG_SIZE_INPUT_HEIGHT(v) ((v & 0xffff) << 16) @@ -93,6 +101,7 @@ struct ipu_pre { dma_addr_t buffer_paddr; void *buffer_virt; bool in_use; + unsigned int safe_window_end; };

static DEFINE_MUTEX(ipu_pre_list_mutex); @@ -160,6 +169,9 @@ void ipu_pre_configure(struct ipu_pre *pre, unsigned int width, u32 active_bpp = info->cpp[0] >> 1; u32 val;

+ /* calculate safe window for ctrl register updates */ + pre->safe_window_end = height - 2; + writel(bufaddr, pre->regs + IPU_PRE_CUR_BUF); writel(bufaddr, pre->regs + IPU_PRE_NEXT_BUF);

@@ -199,7 +211,24 @@ void ipu_pre_configure(struct ipu_pre *pre, unsigned int width,

void ipu_pre_update(struct ipu_pre *pre, unsigned int bufaddr) { + unsigned long timeout = jiffies + msecs_to_jiffies(5); + unsigned short current_yblock; + u32 val; + writel(bufaddr, pre->regs + IPU_PRE_NEXT_BUF); + + do { + if (time_after(jiffies, timeout)) { + dev_warn(pre->dev, "timeout waiting for PRE safe window\n"); + return; + } + + val = readl(pre->regs + IPU_PRE_STORE_ENG_STATUS); + current_yblock = + (val >> IPU_PRE_STORE_ENG_STATUS_STORE_BLOCK_Y_SHIFT) & + IPU_PRE_STORE_ENG_STATUS_STORE_BLOCK_Y_MASK; + } while (current_yblock == 0 || current_yblock >= pre->safe_window_end); + writel(IPU_PRE_CTRL_SDW_UPDATE, pre->regs + IPU_PRE_CTRL_SET); }