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authorSerge Semin <Sergey.Semin@baikalelectronics.ru>2020-07-23 03:58:47 +0300
committerVinod Koul <vkoul@kernel.org>2020-07-27 14:30:55 +0530
commitca7f2851712e7072e8f327882dc4bdaaae3a8079 (patch)
tree6b81cd3579d0e7643c2a64f5f5d679097cb36284 /drivers/dma/dw
parent585d35451e94b2e1b0bf59ef55d3b4a1c8ab3d77 (diff)
dmaengine: dw: Introduce max burst length hw config
IP core of the DW DMA controller may be synthesized with different max burst length of the transfers per each channel. According to Synopsis having the fixed maximum burst transactions length may provide some performance gain. At the same time setting up the source and destination multi size exceeding the max burst length limitation may cause a serious problems. In our case the DMA transaction just hangs up. In order to fix this lets introduce the max burst length platform config of the DW DMA controller device and don't let the DMA channels configuration code exceed the burst length hardware limitation. Note the maximum burst length parameter can be detected either in runtime from the DWC parameter registers or from the dedicated DT property. Depending on the IP core configuration the maximum value can vary from channel to channel so by overriding the channel slave max_burst capability we make sure a DMA consumer will get the channel-specific max burst length. Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20200723005848.31907-10-Sergey.Semin@baikalelectronics.ru Signed-off-by: Vinod Koul <vkoul@kernel.org>
Diffstat (limited to 'drivers/dma/dw')
-rw-r--r--drivers/dma/dw/core.c16
-rw-r--r--drivers/dma/dw/of.c5
-rw-r--r--drivers/dma/dw/regs.h2
3 files changed, 23 insertions, 0 deletions
diff --git a/drivers/dma/dw/core.c b/drivers/dma/dw/core.c
index afe5a2e465af..588b9bae827c 100644
--- a/drivers/dma/dw/core.c
+++ b/drivers/dma/dw/core.c
@@ -791,6 +791,11 @@ static int dwc_config(struct dma_chan *chan, struct dma_slave_config *sconfig)
memcpy(&dwc->dma_sconfig, sconfig, sizeof(*sconfig));
+ dwc->dma_sconfig.src_maxburst =
+ clamp(dwc->dma_sconfig.src_maxburst, 0U, dwc->max_burst);
+ dwc->dma_sconfig.dst_maxburst =
+ clamp(dwc->dma_sconfig.dst_maxburst, 0U, dwc->max_burst);
+
dw->encode_maxburst(dwc, &dwc->dma_sconfig.src_maxburst);
dw->encode_maxburst(dwc, &dwc->dma_sconfig.dst_maxburst);
@@ -1049,6 +1054,13 @@ static void dwc_free_chan_resources(struct dma_chan *chan)
dev_vdbg(chan2dev(chan), "%s: done\n", __func__);
}
+static void dwc_caps(struct dma_chan *chan, struct dma_slave_caps *caps)
+{
+ struct dw_dma_chan *dwc = to_dw_dma_chan(chan);
+
+ caps->max_burst = dwc->max_burst;
+}
+
int do_dma_probe(struct dw_dma_chip *chip)
{
struct dw_dma *dw = chip->dw;
@@ -1189,9 +1201,12 @@ int do_dma_probe(struct dw_dma_chip *chip)
dwc->nollp =
(dwc_params >> DWC_PARAMS_MBLK_EN & 0x1) == 0 ||
(dwc_params >> DWC_PARAMS_HC_LLP & 0x1) == 1;
+ dwc->max_burst =
+ (0x4 << (dwc_params >> DWC_PARAMS_MSIZE & 0x7));
} else {
dwc->block_size = pdata->block_size;
dwc->nollp = !pdata->multi_block[i];
+ dwc->max_burst = pdata->max_burst[i] ?: DW_DMA_MAX_BURST;
}
}
@@ -1214,6 +1229,7 @@ int do_dma_probe(struct dw_dma_chip *chip)
dw->dma.device_prep_dma_memcpy = dwc_prep_dma_memcpy;
dw->dma.device_prep_slave_sg = dwc_prep_slave_sg;
+ dw->dma.device_caps = dwc_caps;
dw->dma.device_config = dwc_config;
dw->dma.device_pause = dwc_pause;
dw->dma.device_resume = dwc_resume;
diff --git a/drivers/dma/dw/of.c b/drivers/dma/dw/of.c
index 9e27831dee32..1474b3817ef4 100644
--- a/drivers/dma/dw/of.c
+++ b/drivers/dma/dw/of.c
@@ -98,6 +98,11 @@ struct dw_dma_platform_data *dw_dma_parse_dt(struct platform_device *pdev)
pdata->multi_block[tmp] = 1;
}
+ if (of_property_read_u32_array(np, "snps,max-burst-len", pdata->max_burst,
+ nr_channels)) {
+ memset32(pdata->max_burst, DW_DMA_MAX_BURST, nr_channels);
+ }
+
if (!of_property_read_u32(np, "snps,dma-protection-control", &tmp)) {
if (tmp > CHAN_PROTCTL_MASK)
return NULL;
diff --git a/drivers/dma/dw/regs.h b/drivers/dma/dw/regs.h
index 1ab840b06e79..76654bd13c1a 100644
--- a/drivers/dma/dw/regs.h
+++ b/drivers/dma/dw/regs.h
@@ -126,6 +126,7 @@ struct dw_dma_regs {
/* Bitfields in DWC_PARAMS */
#define DWC_PARAMS_MBLK_EN 11 /* multi block transfer */
#define DWC_PARAMS_HC_LLP 13 /* set LLP register to zero */
+#define DWC_PARAMS_MSIZE 16 /* max group transaction size */
/* bursts size */
enum dw_dma_msize {
@@ -284,6 +285,7 @@ struct dw_dma_chan {
/* hardware configuration */
unsigned int block_size;
bool nollp;
+ u32 max_burst;
/* custom slave configuration */
struct dw_dma_slave dws;