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    SubjectRe: [PATCH v2] dmaengine: tegra-apb: proper default init of channel slave_id
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    On 22/04/16 13:44, Shardar Shariff Md wrote:
    > Initialize default channel slave_id(req_sel) to invalid id
    > (i.e max supported slave id + 1) to avoid overwriting of slave_id
    > during tegra_dma_slave_config() with client data if slave_id
    > is not initialized through DT
    >
    > Signed-off-by: Shardar Shariff Md <smohammed@nvidia.com>
    >
    > ---
    > - Instead of initializing the slave id to -1 define macros for
    > max slave id and invalid slave id and do the checks accordingly.
    > ---
    > drivers/dma/tegra20-apb-dma.c | 13 +++++++++++--
    > 1 file changed, 11 insertions(+), 2 deletions(-)
    >
    > diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
    > index 3871f29..2957e26 100644
    > --- a/drivers/dma/tegra20-apb-dma.c
    > +++ b/drivers/dma/tegra20-apb-dma.c
    > @@ -114,6 +114,9 @@
    > /* Channel base address offset from APBDMA base address */
    > #define TEGRA_APBDMA_CHANNEL_BASE_ADD_OFFSET 0x1000
    >
    > +#define TEGRA_APBDMA_SLAVE_ID_MAX 31
    > +#define TEGRA_APBDMA_SLAVE_ID_INVALID (TEGRA_APBDMA_SLAVE_ID_MAX + 1)
    > +
    > struct tegra_dma;
    >
    > /*
    > @@ -353,7 +356,7 @@ static int tegra_dma_slave_config(struct dma_chan *dc,
    > }
    >
    > memcpy(&tdc->dma_sconfig, sconfig, sizeof(*sconfig));
    > - if (!tdc->slave_id)
    > + if (tdc->slave_id == TEGRA_APBDMA_SLAVE_ID_INVALID)
    > tdc->slave_id = sconfig->slave_id;
    > tdc->config_init = true;
    > return 0;
    > @@ -1236,7 +1239,7 @@ static void tegra_dma_free_chan_resources(struct dma_chan *dc)
    > }
    > pm_runtime_put(tdma->dev);
    >
    > - tdc->slave_id = 0;
    > + tdc->slave_id = TEGRA_APBDMA_SLAVE_ID_INVALID;
    > }
    >
    > static struct dma_chan *tegra_dma_of_xlate(struct of_phandle_args *dma_spec,
    > @@ -1253,6 +1256,11 @@ static struct dma_chan *tegra_dma_of_xlate(struct of_phandle_args *dma_spec,
    > tdc = to_tegra_dma_chan(chan);
    > tdc->slave_id = dma_spec->args[0];
    >
    > + if (tdc->slave_id > TEGRA_APBDMA_SLAVE_ID_MAX) {
    > + dev_err(tdc2dev(tdc), "Invalid slave id\n");
    > + return NULL;
    > + }

    Please move this test to before the dma_get_any_slave_channel(),
    otherwise we could leak the DMA channel!

    Cheers
    Jon

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