diff options
Diffstat (limited to 'target/linux/pistachio/patches-5.15/105-spi-img-spfi-RX-maximum-burst-size-for-DMA-is-8.patch')
| -rw-r--r-- | target/linux/pistachio/patches-5.15/105-spi-img-spfi-RX-maximum-burst-size-for-DMA-is-8.patch | 59 |
1 files changed, 0 insertions, 59 deletions
diff --git a/target/linux/pistachio/patches-5.15/105-spi-img-spfi-RX-maximum-burst-size-for-DMA-is-8.patch b/target/linux/pistachio/patches-5.15/105-spi-img-spfi-RX-maximum-burst-size-for-DMA-is-8.patch deleted file mode 100644 index 5418503816..0000000000 --- a/target/linux/pistachio/patches-5.15/105-spi-img-spfi-RX-maximum-burst-size-for-DMA-is-8.patch +++ /dev/null @@ -1,59 +0,0 @@ -From 56466f505f58f44b69feb7eaed3b506842800456 Mon Sep 17 00:00:00 2001 -From: Ionela Voinescu <ionela.voinescu@imgtec.com> -Date: Tue, 1 Mar 2016 17:49:45 +0000 -Subject: spi: img-spfi: RX maximum burst size for DMA is 8 - -The depth of the FIFOs is 16 bytes. The DMA request line is tied -to the half full/empty (depending on the use of the TX or RX FIFO) -threshold. For the TX FIFO, if you set a burst size of 8 (equal to -half the depth) the first burst goes into FIFO without any issues, -but due the latency involved (the time the data leaves the DMA -engine to the time it arrives at the FIFO), the DMA might trigger -another burst of 8. But given that there is no space for 2 additonal -bursts of 8, this would result in a failure. Therefore, we have to -keep the burst size for TX to 4 to accomodate for an extra burst. - -For the read (RX) scenario, the DMA request line goes high when -there is at least 8 entries in the FIFO (half full), and we can -program the burst size to be 8 because the risk of accidental burst -does not exist. The DMA engine will not trigger another read until -the read data for all the burst it has sent out has been received. - -While here, move the burst size setting outside of the if/else branches -as they have the same value for both 8 and 32 bit data widths. - -Signed-off-by: Ionela Voinescu <ionela.voinescu@imgtec.com> ---- - drivers/spi/spi-img-spfi.c | 6 ++---- - 1 file changed, 2 insertions(+), 4 deletions(-) - ---- a/drivers/spi/spi-img-spfi.c -+++ b/drivers/spi/spi-img-spfi.c -@@ -338,12 +338,11 @@ static int img_spfi_start_dma(struct spi - if (xfer->len % 4 == 0) { - rxconf.src_addr = spfi->phys + SPFI_RX_32BIT_VALID_DATA; - rxconf.src_addr_width = 4; -- rxconf.src_maxburst = 4; - } else { - rxconf.src_addr = spfi->phys + SPFI_RX_8BIT_VALID_DATA; - rxconf.src_addr_width = 1; -- rxconf.src_maxburst = 4; - } -+ rxconf.src_maxburst = 8; - dmaengine_slave_config(spfi->rx_ch, &rxconf); - - rxdesc = dmaengine_prep_slave_sg(spfi->rx_ch, xfer->rx_sg.sgl, -@@ -362,12 +361,11 @@ static int img_spfi_start_dma(struct spi - if (xfer->len % 4 == 0) { - txconf.dst_addr = spfi->phys + SPFI_TX_32BIT_VALID_DATA; - txconf.dst_addr_width = 4; -- txconf.dst_maxburst = 4; - } else { - txconf.dst_addr = spfi->phys + SPFI_TX_8BIT_VALID_DATA; - txconf.dst_addr_width = 1; -- txconf.dst_maxburst = 4; - } -+ txconf.dst_maxburst = 4; - dmaengine_slave_config(spfi->tx_ch, &txconf); - - txdesc = dmaengine_prep_slave_sg(spfi->tx_ch, xfer->tx_sg.sgl, |