Hello Dave Jiang,
The patch deb9541f5052: "dmaengine: check device and channel list for
empty" from Jun 26, 2020, leads to the following static checker
warnings:
drivers/mmc/host/omap_hsmmc.c:1959 omap_hsmmc_probe() warn: 'host->rx_chan' can also be NULL
drivers/mmc/host/omap_hsmmc.c:1959 omap_hsmmc_probe() warn: 'host->tx_chan' can also be NULL
drivers/media/platform/xilinx/xilinx-dma.c:736 xvip_dma_init() warn: 'dma->dma' can also be NULL
drivers/spi/spi-fsl-dspi.c:520 dspi_request_dma() warn: 'dma->chan_tx' can also be NULL
drivers/spi/spi-fsl-dspi.c:528 dspi_request_dma() warn: 'dma->chan_rx' can also be NULL
drivers/iio/adc/ti_am335x_adc.c:565 tiadc_request_dma() warn: 'dma->chan' can also be NULL
drivers/iio/adc/stm32-dfsdm-adc.c:1381 stm32_dfsdm_dma_request() warn: 'adc->dma_chan' can also be NULL
drivers/iio/adc/stm32-adc.c:1837 stm32_adc_dma_request() warn: 'adc->dma_chan' can also be NULL
drivers/iio/adc/at91-sama5d2_adc.c:1520 at91_adc_dma_init() warn: 'st->dma_st.dma_chan' can also be NULL
sound/soc/ti/davinci-mcasp.c:1902 davinci_mcasp_get_dma_type() warn: 'chan' can also be NULL
drivers/mmc/host/omap_hsmmc.c
1937
1938 host->rx_chan = dma_request_chan(&pdev->dev, "rx");
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The dma_request_chan() function used to only return error pointers or
a valid pointer. We need to update the comments at the start of the
function to explain about the new NULL return.
1939 if (IS_ERR(host->rx_chan)) {
1940 dev_err(mmc_dev(host->mmc), "RX DMA channel request failed\n");
1941 ret = PTR_ERR(host->rx_chan);
1942 goto err_irq;
1943 }
1944
1945 host->tx_chan = dma_request_chan(&pdev->dev, "tx");
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1946 if (IS_ERR(host->tx_chan)) {
1947 dev_err(mmc_dev(host->mmc), "TX DMA channel request failed\n");
1948 ret = PTR_ERR(host->tx_chan);
1949 goto err_irq;
1950 }
1951
1952 /*
1953 * Limit the maximum segment size to the lower of the request size
1954 * and the DMA engine device segment size limits. In reality, with
1955 * 32-bit transfers, the DMA engine can do longer segments than this
1956 * but there is no way to represent that in the DMA model - if we
1957 * increase this figure here, we get warnings from the DMA API debug.
1958 */
1959 mmc->max_seg_size = min3(mmc->max_req_size,
1960 dma_get_max_seg_size(host->rx_chan->device->dev),
^^^^^^^^^^^^^^^
This will Oops.
1961 dma_get_max_seg_size(host->tx_chan->device->dev));
1962
1963 /* Request IRQ for MMC operations */
1964 ret = devm_request_irq(&pdev->dev, host->irq, omap_hsmmc_irq, 0,
1965 mmc_hostname(mmc), host);
1966 if (ret) {
1967 dev_err(mmc_dev(host->mmc), "Unable to grab HSMMC IRQ\n");
regards,
dan carpenter
