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authorRabin Vincent <rabin.vincent@stericsson.com>2011-01-25 11:18:05 +0100
committerDan Williams <dan.j.williams@intel.com>2011-01-30 22:27:15 -0800
commit262d2915d4f11e5e78e432ab68f0ee034ef3f75f (patch)
tree9c14e8b8518fbd377ba96826bcb03bb02f89ed34 /drivers/dma
parentcb9ab2d8e4661c811d5e9a8e687b6f736690c90e (diff)
dma40: ensure event lines get enabled
The controller sometimes fails to register the enable of the event line when both src and dst event lines are used on the same logical channel. Implement the recommended software workaround, which is to retry the write until it works. Acked-by: Per Forlin <per.forlin@stericsson.com> Acked-by: Jonas Aaberg <jonas.aberg@stericsson.com> Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com> Signed-off-by: Linus Walleij <linus.walleij@stericsson.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers/dma')
-rw-r--r--drivers/dma/ste_dma40.c63
1 files changed, 46 insertions, 17 deletions
diff --git a/drivers/dma/ste_dma40.c b/drivers/dma/ste_dma40.c
index 52013ed4b44..42c88fc2881 100644
--- a/drivers/dma/ste_dma40.c
+++ b/drivers/dma/ste_dma40.c
@@ -303,6 +303,11 @@ struct d40_reg_val {
unsigned int val;
};
+static struct device *chan2dev(struct d40_chan *d40c)
+{
+ return &d40c->chan.dev->device;
+}
+
static int d40_pool_lli_alloc(struct d40_desc *d40d,
int lli_len, bool is_log)
{
@@ -701,17 +706,46 @@ static void d40_term_all(struct d40_chan *d40c)
d40c->busy = false;
}
+static void __d40_config_set_event(struct d40_chan *d40c, bool enable,
+ u32 event, int reg)
+{
+ void __iomem *addr = d40c->base->virtbase + D40_DREG_PCBASE
+ + d40c->phy_chan->num * D40_DREG_PCDELTA + reg;
+ int tries;
+
+ if (!enable) {
+ writel((D40_DEACTIVATE_EVENTLINE << D40_EVENTLINE_POS(event))
+ | ~D40_EVENTLINE_MASK(event), addr);
+ return;
+ }
+
+ /*
+ * The hardware sometimes doesn't register the enable when src and dst
+ * event lines are active on the same logical channel. Retry to ensure
+ * it does. Usually only one retry is sufficient.
+ */
+ tries = 100;
+ while (--tries) {
+ writel((D40_ACTIVATE_EVENTLINE << D40_EVENTLINE_POS(event))
+ | ~D40_EVENTLINE_MASK(event), addr);
+
+ if (readl(addr) & D40_EVENTLINE_MASK(event))
+ break;
+ }
+
+ if (tries != 99)
+ dev_dbg(chan2dev(d40c),
+ "[%s] workaround enable S%cLNK (%d tries)\n",
+ __func__, reg == D40_CHAN_REG_SSLNK ? 'S' : 'D',
+ 100 - tries);
+
+ WARN_ON(!tries);
+}
+
static void d40_config_set_event(struct d40_chan *d40c, bool do_enable)
{
- u32 val;
unsigned long flags;
- /* Notice, that disable requires the physical channel to be stopped */
- if (do_enable)
- val = D40_ACTIVATE_EVENTLINE;
- else
- val = D40_DEACTIVATE_EVENTLINE;
-
spin_lock_irqsave(&d40c->phy_chan->lock, flags);
/* Enable event line connected to device (or memcpy) */
@@ -719,20 +753,15 @@ static void d40_config_set_event(struct d40_chan *d40c, bool do_enable)
(d40c->dma_cfg.dir == STEDMA40_PERIPH_TO_PERIPH)) {
u32 event = D40_TYPE_TO_EVENT(d40c->dma_cfg.src_dev_type);
- writel((val << D40_EVENTLINE_POS(event)) |
- ~D40_EVENTLINE_MASK(event),
- d40c->base->virtbase + D40_DREG_PCBASE +
- d40c->phy_chan->num * D40_DREG_PCDELTA +
- D40_CHAN_REG_SSLNK);
+ __d40_config_set_event(d40c, do_enable, event,
+ D40_CHAN_REG_SSLNK);
}
+
if (d40c->dma_cfg.dir != STEDMA40_PERIPH_TO_MEM) {
u32 event = D40_TYPE_TO_EVENT(d40c->dma_cfg.dst_dev_type);
- writel((val << D40_EVENTLINE_POS(event)) |
- ~D40_EVENTLINE_MASK(event),
- d40c->base->virtbase + D40_DREG_PCBASE +
- d40c->phy_chan->num * D40_DREG_PCDELTA +
- D40_CHAN_REG_SDLNK);
+ __d40_config_set_event(d40c, do_enable, event,
+ D40_CHAN_REG_SDLNK);
}
spin_unlock_irqrestore(&d40c->phy_chan->lock, flags);