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    Subject[PATCH AUTOSEL 4.14 21/36] dmaengine: at_xdmac: Fix wrongfull report of a channel as in use
    Date
    From: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>

    [ Upstream commit dc3f595b6617ebc0307e0ce151e8f2f2b2489b95 ]

    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>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    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 94236ec9d4100..4db2cd1c611de 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_bh(&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);
    --
    2.19.1
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