Messages in this thread | | | Subject | Re: [PATCH v6 2/4] dmaengine: tegra: Add tegra gpcdma driver | From | Jon Hunter <> | Date | Thu, 23 Sep 2021 14:20:30 +0100 |
| |
On 23/09/2021 13:51, Akhil R wrote: >> On 22/09/2021 15:46, Akhil R wrote: >>> >>>> On 17/09/2021 15:11, Akhil R wrote: >>>>> +static int tegra_dma_slave_config(struct dma_chan *dc, >>>>> + struct dma_slave_config *sconfig) { >>>>> + struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc); >>>>> + >>>>> + if (tdc->dma_desc) { >>>>> + dev_err(tdc2dev(tdc), "Configuration not allowed\n"); >>>>> + return -EBUSY; >>>>> + } >>>>> + >>>>> + memcpy(&tdc->dma_sconfig, sconfig, sizeof(*sconfig)); >>>>> + if (tdc->slave_id == -1) >>>>> + tdc->slave_id = sconfig->slave_id; >>>>> + >>>>> + tdc->config_init = true; >>>>> + return 0; >>>>> +} >>>> >>>> So you have a function to reserve a slave ID, but you don't check >>>> here if it is already reserved. >>> slave-id is reserved considering the direction as well. >>> 'direction' is available only during prep_slave_sg function, I guess. >> >> Sorry I don't understand what you mean by that. > I mean, it would not be possible to check if the sid is in use without knowing > if the direction is MEM_TO_DEV or DEV_TO_MEM. The bitmask to check the > sid reservation is separate for MEM_TO_DEV and DEV_TO_MEM. > To get the direction parameter, we would need to wait till dma_prep_slave_sg > is called, I guess. I saw in the documentation that the 'direction' element in > dma_slave_config struct is deprecated and should use the value passed to > dma_prep_slave_sg().
Do we even need to worry about slave_id here? Typically the slave_id is coming from device-tree and so is handled by tegra_dma_of_xlate(). I would drop this unless there is an actual use-case we need to support that uses this.
Jon
-- nvpublic
| |