On 8/22/22 09:56, Akhil R wrote: >> 19.08.2022 18:15, Dmitry Osipenko пишет: >>> 19.08.2022 15:23, Akhil R пишет: >>>> if (of_device_is_compatible(np, "nvidia,tegra210-i2c-vi")) >>>> i2c_dev->is_vi = true; >>>> + else >>>> + i2c_dev->dma_support = !!(of_find_property(np, "dmas", >>>> + NULL)); >>> >>> 1. You leak the np returned by of_find_property(). >>> >>> 2. There is device_property_read_bool() for this kind of >>> property-exists checks. > Okay. I went by the implementation in of_dma_request_slave_channel() to > check 'dmas'. > >>> >>> 3. If "dmas" is missing in DT, then dma_request_chan() should return >>> NULL and everything will work fine. I suppose you haven't tried to >>> test this code. >> >> Although, no. It should return ERR_PTR(-ENODEV) and then you should check >> the return code. > Yes. Agree that it is more agnostic to check for ERR_PTR(-ENODEV). But since I > call tegra_init_dma() for every large transfer until DMA is initialized, wouldn't > it be better to have a flag inside the driver so that we do not have to go through > so many functions for every attempted DMA transaction to find out that the DT > properties don't exist? > > Shall I just put i2c_dev->dma_support = true here since DMA is supported by > hardware? It would turn false if dma_request_chan() returns something other > than -EPROBE_DEFER. > > if (of_device_is_compatible(np, "nvidia,tegra210-i2c-vi")) > i2c_dev->is_vi = true; > + else > + i2c_dev->dma_support = true; The code already has dma_mode for that. I don't see why another variable is needed. Either add new generic dma_request_chan_optional() that will return NULL if channel is not available and make Tegra I2C driver to use it, or handle the error code returned by dma_request_chan(). -- Best regards, Dmitry
