On Thu, Jul 23, 2015 at 05:10:42PM +0800, Leilk Liu wrote:
This basically seems fine but there's a couple of issues that should be
relatively easy to fix:
> + mdata->cur_transfer = xfer;
> + mtk_spi_prepare_transfer(master, xfer);
> + mtk_spi_setup_packet(master, xfer);
> +
> + cnt = (xfer->len % 4) ? (xfer->len / 4 + 1) : (xfer->len / 4);
Please write this as an if statement for legibility.
> +static bool mtk_spi_can_dma(struct spi_master *master,
> + struct spi_device *spi,
> + struct spi_transfer *xfer)
> +{
> + struct mtk_spi *mdata = spi_master_get_devdata(master);
> +
> + if (xfer->len > MTK_SPI_MAX_FIFO_SIZE)
> + mdata->use_dma = true;
> + else
> + mdata->use_dma = false;
> +
> + return mdata->use_dma;
> +}
This is broken since can_dma() can be called multiple transfers before
actually doing a transfer (the current implementation loops over all
transfers in a message before starting the message) - you can't store
any local data. The transfer_one() function should do another can_dma()
check to decide if it can DMA, it shouldn't rely on driver global data.
> + if (!mdata->use_dma) {
> + if (trans->rx_buf) {
This should be a variable set when doing the transfer (or perhaps based
on checking spi->cur_xfer with can_dma()).
> + for (i = 0; i < trans->len; i++) {
> + if (i % 4 == 0)
> + reg_val =
> + readl(mdata->base + SPI_RX_DATA_REG);
> + *((u8 *)(trans->rx_buf + i)) =
> + (reg_val >> ((i % 4) * 8)) & 0xff;
This isn't the clearest code ever... a comment would help.
> + if (mdata->tx_sgl && (mdata->tx_sgl_len == 0)) {
> + mdata->tx_sgl = sg_next(mdata->tx_sgl);
> + if (mdata->tx_sgl) {
> + trans->tx_dma = sg_dma_address(mdata->tx_sgl);
> + mdata->tx_sgl_len = sg_dma_len(mdata->tx_sgl);
> + }
> + }
There's a *lot* of code in this interrupt handler, and a lot of it looks
an awful lot like the contents of mtk_spi_dma_transfer() has been
cut'n'pasted in. The shared code should all be factored out into a
function called from both places.
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