Re: [PATCH 11/15] tty: msm_serial: use dmaengine_prep_slave_sg()

[Jiri Slaby]

On 17. 04. 24, 14:45, Marek Szyprowski wrote:
> I alse tried to change the "if (dma->mapped)" check in msm_start_tx() to:
>
> 1. if (dma->tx_sg.length)
>
> 2. if (dma->tx_sg.page_link & ~SG_PAGE_LINK_MASK)
>
> but none of the above worked what is really strange and incomprehensible
> for me.

Aaaah, nevermind, what about this?

Two bugs:
1) dma_map_sg() returns the number of mapped entries. Not zero!
2) And I forgot to zero tx_sg in case of error.

--- a/drivers/tty/serial/msm_serial.c
+++ b/drivers/tty/serial/msm_serial.c
@@ -506,8 +506,8 @@ static int msm_handle_tx_dma(struct msm_port 
*msm_port, unsigned int count)
        kfifo_dma_out_prepare(&tport->xmit_fifo, &dma->tx_sg, 1, count);

        ret = dma_map_sg(port->dev, &dma->tx_sg, 1, dma->dir);
-       if (ret)
-               return ret;
+       if (!ret)
+               goto zero_out;

        dma->desc = dmaengine_prep_slave_sg(dma->chan, &dma->tx_sg, 1,
                                                DMA_MEM_TO_DEV,
@@ -548,6 +548,7 @@ static int msm_handle_tx_dma(struct msm_port 
*msm_port, unsigned int count)
        return 0;
 unmap:
        dma_unmap_sg(port->dev, &dma->tx_sg, 1, dma->dir);
+zero_out:
        sg_init_table(&dma->tx_sg, 1);
        return ret;
 }


thanks,
--
js
suse labs