| Message ID | 20201022151250.3236335-1-olteanv@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | tty: serial: fsl_lpuart: LS1021A has a FIFO size of 32 datawords | expand |
On Thu, Oct 22, 2020 at 06:12:50PM +0300, Vladimir Oltean wrote: > From: Vladimir Oltean <vladimir.oltean@nxp.com> > > Similar to the workaround applied by Michael Walle in commit > c2f448cff22a ("tty: serial: fsl_lpuart: add LS1028A support"), it turns > out that the LPUARTx_FIFO encoding for fields TXFIFOSIZE and RXFIFOSIZE > is the same for LS1028A as for LS1021A. > > The RXFIFOSIZE in the Layerscape SoCs is fixed at this value: > 101 Receive FIFO/Buffer depth = 32 datawords. > > When Andy Duan wrote the commit in Fixes: below, he assumed that the 101 > encoding means 64 datawords. But this is not true for Layerscape. So > that commit broke LS1021A, and this patch is extending the workaround > for LS1028A which appeared in the meantime, to fix that breakage. > > When the driver thinks that it has a deeper FIFO than it really has, > getty (user space) output gets truncated. > > Many thanks to Michael for suggesting this! > > Fixes: f77ebb241ce0 ("tty: serial: fsl_lpuart: correct the FIFO depth size") > Suggested-by: Michael Walle <michael@walle.cc> > Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> > --- Please don't merge this yet. The patch works, but the commit message is a mess. Right now I suspect there might be some issues in the documentation. I'll return with a v2 when I get that clarified.
From: Vladimir Oltean <olteanv@gmail.com> Sent: Thursday, October 22, 2020 11:13 PM > From: Vladimir Oltean <vladimir.oltean@nxp.com> > > Similar to the workaround applied by Michael Walle in commit c2f448cff22a > ("tty: serial: fsl_lpuart: add LS1028A support"), it turns out that the > LPUARTx_FIFO encoding for fields TXFIFOSIZE and RXFIFOSIZE is the same for > LS1028A as for LS1021A. > > The RXFIFOSIZE in the Layerscape SoCs is fixed at this value: > 101 Receive FIFO/Buffer depth = 32 datawords. > > When Andy Duan wrote the commit in Fixes: below, he assumed that the 101 > encoding means 64 datawords. But this is not true for Layerscape. So that > commit broke LS1021A, and this patch is extending the workaround for LS1028A > which appeared in the meantime, to fix that breakage. > > When the driver thinks that it has a deeper FIFO than it really has, getty (user > space) output gets truncated. > > Many thanks to Michael for suggesting this! > > Fixes: f77ebb241ce0 ("tty: serial: fsl_lpuart: correct the FIFO depth size") > Suggested-by: Michael Walle <michael@walle.cc> > Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Layerscape has different define for the FIFO size. Reviewed-by: Fugang Duan <fugang.duan@nxp.com> > --- > drivers/tty/serial/fsl_lpuart.c | 13 +++++++------ > 1 file changed, 7 insertions(+), 6 deletions(-) > > diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index > ff4b88c637d0..bd047e1f9bea 100644 > --- a/drivers/tty/serial/fsl_lpuart.c > +++ b/drivers/tty/serial/fsl_lpuart.c > @@ -314,9 +314,10 @@ MODULE_DEVICE_TABLE(of, lpuart_dt_ids); > /* Forward declare this for the dma callbacks*/ static void > lpuart_dma_tx_complete(void *arg); > > -static inline bool is_ls1028a_lpuart(struct lpuart_port *sport) > +static inline bool is_layerscape_lpuart(struct lpuart_port *sport) > { > - return sport->devtype == LS1028A_LPUART; > + return (sport->devtype == LS1021A_LPUART || > + sport->devtype == LS1028A_LPUART); > } > > static inline bool is_imx8qxp_lpuart(struct lpuart_port *sport) @@ -1701,11 > +1702,11 @@ static int lpuart32_startup(struct uart_port *port) > > UARTFIFO_FIFOSIZE_MASK); > > /* > - * The LS1028A has a fixed length of 16 words. Although it supports > the > - * RX/TXSIZE fields their encoding is different. Eg the reference > manual > - * states 0b101 is 16 words. > + * The LS1021A and LS1028A have a fixed FIFO depth of 16 words. > + * Although they support the RX/TXSIZE fields, their encoding is > + * different. Eg the reference manual states 0b101 is 16 words. > */ > - if (is_ls1028a_lpuart(sport)) { > + if (is_layerscape_lpuart(sport)) { > sport->rxfifo_size = 16; > sport->txfifo_size = 16; > sport->port.fifosize = sport->txfifo_size; > -- > 2.25.1
diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index ff4b88c637d0..bd047e1f9bea 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -314,9 +314,10 @@ MODULE_DEVICE_TABLE(of, lpuart_dt_ids); /* Forward declare this for the dma callbacks*/ static void lpuart_dma_tx_complete(void *arg); -static inline bool is_ls1028a_lpuart(struct lpuart_port *sport) +static inline bool is_layerscape_lpuart(struct lpuart_port *sport) { - return sport->devtype == LS1028A_LPUART; + return (sport->devtype == LS1021A_LPUART || + sport->devtype == LS1028A_LPUART); } static inline bool is_imx8qxp_lpuart(struct lpuart_port *sport) @@ -1701,11 +1702,11 @@ static int lpuart32_startup(struct uart_port *port) UARTFIFO_FIFOSIZE_MASK); /* - * The LS1028A has a fixed length of 16 words. Although it supports the - * RX/TXSIZE fields their encoding is different. Eg the reference manual - * states 0b101 is 16 words. + * The LS1021A and LS1028A have a fixed FIFO depth of 16 words. + * Although they support the RX/TXSIZE fields, their encoding is + * different. Eg the reference manual states 0b101 is 16 words. */ - if (is_ls1028a_lpuart(sport)) { + if (is_layerscape_lpuart(sport)) { sport->rxfifo_size = 16; sport->txfifo_size = 16; sport->port.fifosize = sport->txfifo_size;