| Message ID | 1375538956-15862-2-git-send-email-shijie8@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sat, Aug 03, 2013 at 10:09:14AM -0400, Huang Shijie wrote: > From: Huang Shijie <b32955@freescale.com> > > The original DMA support works only when RTS/CTS is enabled. > (see the "e800163 serial: mxs-auart: add the DMA support for mx28") > But after several patches, DMA support has lost this limit. > (see the "bcc20f9 serial: mxs-auart: move to use generic DMA helper") > > So an UART without the RTS/CTS lines may also enables the DMA support, > in which case the UART may gets unpredictable results. > > This patch adds an optional property for the UART DT node > which indicates the UART has RTS and CTS lines, and it also means you > enable the DMA support for this UART. > > This patch also adds a macro MXS_AUART_RTSCTS, and uses it to check > RTS/CTS before we enable the DMA for the UART. > > Cc: stable@vger.kernel.org > Signed-off-by: Huang Shijie <b32955@freescale.com> > Signed-off-by: Huang Shijie <shijie8@gmail.com> > --- > .../bindings/tty/serial/fsl-mxs-auart.txt | 4 ++++ > drivers/tty/serial/mxs-auart.c | 7 ++++++- > 2 files changed, 10 insertions(+), 1 deletions(-) I don't see how this patch follows the stable kernel guidelines, so I'll take the marking of it off, and queue it up for 3.12. thanks, greg k-h
diff --git a/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt b/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt index 2c00ec6..59a40f1 100644 --- a/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt +++ b/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt @@ -10,6 +10,10 @@ Required properties: Refer to dma.txt and fsl-mxs-dma.txt for details. - dma-names: "rx" for RX channel, "tx" for TX channel. +Optional properties: +- fsl,uart-has-rtscts : Indicate the UART has RTS and CTS lines, + it also means you enable the DMA support for this UART. + Example: auart0: serial@8006a000 { compatible = "fsl,imx28-auart", "fsl,imx23-auart"; diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c index 736e95c..eac7b58 100644 --- a/drivers/tty/serial/mxs-auart.c +++ b/drivers/tty/serial/mxs-auart.c @@ -137,6 +137,7 @@ struct mxs_auart_port { #define MXS_AUART_DMA_ENABLED 0x2 #define MXS_AUART_DMA_TX_SYNC 2 /* bit 2 */ #define MXS_AUART_DMA_RX_READY 3 /* bit 3 */ +#define MXS_AUART_RTSCTS 4 /* bit 4 */ unsigned long flags; unsigned int ctrl; enum mxs_auart_type devtype; @@ -639,7 +640,8 @@ static void mxs_auart_settermios(struct uart_port *u, * we can only implement the DMA support for auart * in mx28. */ - if (is_imx28_auart(s) && (s->flags & MXS_AUART_DMA_CONFIG)) { + if (is_imx28_auart(s) && (s->flags & MXS_AUART_DMA_CONFIG) + && test_bit(MXS_AUART_RTSCTS, &s->flags)) { if (!mxs_auart_dma_init(s)) /* enable DMA tranfer */ ctrl2 |= AUART_CTRL2_TXDMAE | AUART_CTRL2_RXDMAE @@ -1009,6 +1011,9 @@ static int serial_mxs_probe_dt(struct mxs_auart_port *s, s->flags |= MXS_AUART_DMA_CONFIG; + if (of_get_property(np, "fsl,uart-has-rtscts", NULL)) + set_bit(MXS_AUART_RTSCTS, &s->flags); + return 0; }