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Subject[PATCH v2] dmaengine: at_xdmac: Fix wrongfull report of a channel as in use
Date
From: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>

atchan->status variable is used to store two different information:
- pass channel interrupts status from interrupt handler to tasklet;
- channel information like whether it is cyclic or paused;

This causes a bug when device_terminate_all() is called,
(AT_XDMAC_CHAN_IS_CYCLIC cleared on atchan->status) and then a late End
of Block interrupt arrives (AT_XDMAC_CIS_BIS), which sets bit 0 of
atchan->status. Bit 0 is also used for AT_XDMAC_CHAN_IS_CYCLIC, so when
a new descriptor for a cyclic transfer is created, the driver reports
the channel as in use:

if (test_and_set_bit(AT_XDMAC_CHAN_IS_CYCLIC, &atchan->status)) {
dev_err(chan2dev(chan), "channel currently used\n");
return NULL;
}

This patch fixes the bug by adding a different struct member to keep
the interrupts status separated from the channel status bits.

Fixes: e1f7c9eee707 ("dmaengine: at_xdmac: creation of the atmel eXtended DMA Controller driver")
Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>
---
drivers/dma/at_xdmac.c | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
index 4e557684f792..fe69dccfa0c0 100644
--- a/drivers/dma/at_xdmac.c
+++ b/drivers/dma/at_xdmac.c
@@ -203,6 +203,7 @@ struct at_xdmac_chan {
u32 save_cim;
u32 save_cnda;
u32 save_cndc;
+ u32 irq_status;
unsigned long status;
struct tasklet_struct tasklet;
struct dma_slave_config sconfig;
@@ -1580,8 +1581,8 @@ static void at_xdmac_tasklet(unsigned long data)
struct at_xdmac_desc *desc;
u32 error_mask;

- dev_dbg(chan2dev(&atchan->chan), "%s: status=0x%08lx\n",
- __func__, atchan->status);
+ dev_dbg(chan2dev(&atchan->chan), "%s: status=0x%08x\n",
+ __func__, atchan->irq_status);

error_mask = AT_XDMAC_CIS_RBEIS
| AT_XDMAC_CIS_WBEIS
@@ -1589,15 +1590,15 @@ static void at_xdmac_tasklet(unsigned long data)

if (at_xdmac_chan_is_cyclic(atchan)) {
at_xdmac_handle_cyclic(atchan);
- } else if ((atchan->status & AT_XDMAC_CIS_LIS)
- || (atchan->status & error_mask)) {
+ } else if ((atchan->irq_status & AT_XDMAC_CIS_LIS)
+ || (atchan->irq_status & error_mask)) {
struct dma_async_tx_descriptor *txd;

- if (atchan->status & AT_XDMAC_CIS_RBEIS)
+ if (atchan->irq_status & AT_XDMAC_CIS_RBEIS)
dev_err(chan2dev(&atchan->chan), "read bus error!!!");
- if (atchan->status & AT_XDMAC_CIS_WBEIS)
+ if (atchan->irq_status & AT_XDMAC_CIS_WBEIS)
dev_err(chan2dev(&atchan->chan), "write bus error!!!");
- if (atchan->status & AT_XDMAC_CIS_ROIS)
+ if (atchan->irq_status & AT_XDMAC_CIS_ROIS)
dev_err(chan2dev(&atchan->chan), "request overflow error!!!");

spin_lock(&atchan->lock);
@@ -1652,7 +1653,7 @@ static irqreturn_t at_xdmac_interrupt(int irq, void *dev_id)
atchan = &atxdmac->chan[i];
chan_imr = at_xdmac_chan_read(atchan, AT_XDMAC_CIM);
chan_status = at_xdmac_chan_read(atchan, AT_XDMAC_CIS);
- atchan->status = chan_status & chan_imr;
+ atchan->irq_status = chan_status & chan_imr;
dev_vdbg(atxdmac->dma.dev,
"%s: chan%d: imr=0x%x, status=0x%x\n",
__func__, i, chan_imr, chan_status);
@@ -1666,7 +1667,7 @@ static irqreturn_t at_xdmac_interrupt(int irq, void *dev_id)
at_xdmac_chan_read(atchan, AT_XDMAC_CDA),
at_xdmac_chan_read(atchan, AT_XDMAC_CUBC));

- if (atchan->status & (AT_XDMAC_CIS_RBEIS | AT_XDMAC_CIS_WBEIS))
+ if (atchan->irq_status & (AT_XDMAC_CIS_RBEIS | AT_XDMAC_CIS_WBEIS))
at_xdmac_write(atxdmac, AT_XDMAC_GD, atchan->mask);

tasklet_schedule(&atchan->tasklet);
--
2.17.1
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