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authorFabio Baltieri <fabio.baltieri@linaro.org>2012-12-18 12:25:14 +0100
committerFabio Baltieri <fabio.baltieri@linaro.org>2013-01-14 10:51:08 +0100
commit7407048bec896268b50e3c43c1d012a4764dc210 (patch)
tree259a92df30b4c9e08cc0c2270bc997fa212225cb /drivers/dma
parent7ce529efbcf6fdcb1854e4634adf7f6a18216e81 (diff)
dmaengine: ste_dma40: add software lli support
This patch add support to manage LLI by SW for select phy channels. There is a HW issue in certain controllers due to which on certain occassions HW LLI cannot be used on some physical channels. To avoid the HW issue on a specific phy channel, the phy channel number can be added to the list of soft_lli_channels and there after all the transfers on that channel will use software LLI, for peripheral to memory transfers. SoftLLI introduces relink overhead, that could impact performace for certain use cases. This is based on a previous patch of Narayanan Gopalakrishnan. Cc: Shreshtha Kumar Sahu <shreshthakumar.sahu@stericsson.com> Acked-by: Linus Walleij <linus.walleij@linaro.org> Acked-by: Vinod Koul <vinod.koul@intel.com> Signed-off-by: Fabio Baltieri <fabio.baltieri@linaro.org>
Diffstat (limited to 'drivers/dma')
-rw-r--r--drivers/dma/ste_dma40.c20
1 files changed, 19 insertions, 1 deletions
diff --git a/drivers/dma/ste_dma40.c b/drivers/dma/ste_dma40.c
index e317debdbe5a..2ecefb7113b9 100644
--- a/drivers/dma/ste_dma40.c
+++ b/drivers/dma/ste_dma40.c
@@ -355,6 +355,7 @@ struct d40_lcla_pool {
* @allocated_dst: Same as for src but is dst.
* allocated_dst and allocated_src uses the D40_ALLOC* defines as well as
* event line number.
+ * @use_soft_lli: To mark if the linked lists of channel are managed by SW.
*/
struct d40_phy_res {
spinlock_t lock;
@@ -362,6 +363,7 @@ struct d40_phy_res {
int num;
u32 allocated_src;
u32 allocated_dst;
+ bool use_soft_lli;
};
struct d40_base;
@@ -783,7 +785,16 @@ static void d40_log_lli_to_lcxa(struct d40_chan *chan, struct d40_desc *desc)
* can't link back to the one in LCPA space
*/
if (linkback || (lli_len - lli_current > 1)) {
- curr_lcla = d40_lcla_alloc_one(chan, desc);
+ /*
+ * If the channel is expected to use only soft_lli don't
+ * allocate a lcla. This is to avoid a HW issue that exists
+ * in some controller during a peripheral to memory transfer
+ * that uses linked lists.
+ */
+ if (!(chan->phy_chan->use_soft_lli &&
+ chan->dma_cfg.dir == STEDMA40_PERIPH_TO_MEM))
+ curr_lcla = d40_lcla_alloc_one(chan, desc);
+
first_lcla = curr_lcla;
}
@@ -3063,6 +3074,13 @@ static int __init d40_phy_res_init(struct d40_base *base)
num_phy_chans_avail--;
}
+ /* Mark soft_lli channels */
+ for (i = 0; i < base->plat_data->num_of_soft_lli_chans; i++) {
+ int chan = base->plat_data->soft_lli_chans[i];
+
+ base->phy_res[chan].use_soft_lli = true;
+ }
+
dev_info(base->dev, "%d of %d physical DMA channels available\n",
num_phy_chans_avail, base->num_phy_chans);