From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jon Hunter Subject: Re: [PATCH v2] dmaengine: tegra-apb: proper default init of channel slave_id Date: Fri, 22 Apr 2016 14:33:13 +0100 Message-ID: <571A2819.9000507@nvidia.com> References: <1461329093-20300-1-git-send-email-smohammed@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1461329093-20300-1-git-send-email-smohammed@nvidia.com> Sender: linux-kernel-owner@vger.kernel.org To: Shardar Shariff Md , ldewangan@nvidia.com, vinod.koul@intel.com, dan.j.williams@intel.com, swarren@wwwdotorg.org, thierry.reding@gmail.com, gnurou@gmail.com, dmaengine@vger.kernel.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-tegra@vger.kernel.org Hi Shardar, 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 > > --- > - 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 Sorry, thinking about this some more, given that the ID is programmed into a field in the CSR register could we just define as mask here for the CSR field ... #define TEGRA_APBDMA_CSR_REQ_SEL_MASK 0x1f Note this should be defined with the other CSR register field definitions. > +#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; I believe I mentioned before that here we should ... if (tdc->slave_id != TEGRA_APBDMA_SLAVE_ID_INVALID) return -EBUSY; memcpy(&tdc->dma_sconfig, sconfig, sizeof(*sconfig)); 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; > + } > + > return chan; > } > > @@ -1389,6 +1397,7 @@ static int tegra_dma_probe(struct platform_device *pdev) > &tdma->dma_dev.channels); > tdc->tdma = tdma; > tdc->id = i; > + tdc->slave_id = TEGRA_APBDMA_SLAVE_ID_INVALID; > > tasklet_init(&tdc->tasklet, tegra_dma_tasklet, > (unsigned long)tdc); Otherwise looks good. Cheers Jon