dmaengine: at_xdmac: Fix wrongfull report of a channel as in use

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>
Signed-off-by: Vinod Koul <vkoul@kernel.org>

1 files 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);