| Message ID | 20220317174627.360815-6-miquel.raynal@bootlin.com |
|---|---|
| State | New |
| Headers | show |
| Series | serial: 8250: dw: RZN1 DMA support | expand |
On Thu, Mar 17, 2022 at 06:46:22PM +0100, Miquel Raynal wrote: > The CPR register can give the information whether the IP is DMA capable > or not. Let's extract this information when the CPR register is valid > and use it to discriminate when the DMA cannot be hooked up. > > We assume existing designs either provide a valid CPR register or do not > provide any. ... > + if (!(reg & DW_UART_CPR_DMA_EXTRA)) > + data->no_dma = 1; My question still remains: Does this bit is _guaranteed_ to be set when this IP is integrated on all possible DMAs?
Hi Andy, andriy.shevchenko@linux.intel.com wrote on Fri, 18 Mar 2022 15:50:12 +0200: > On Thu, Mar 17, 2022 at 06:46:22PM +0100, Miquel Raynal wrote: > > The CPR register can give the information whether the IP is DMA capable > > or not. Let's extract this information when the CPR register is valid > > and use it to discriminate when the DMA cannot be hooked up. > > > > We assume existing designs either provide a valid CPR register or do not > > provide any. > > ... > > > + if (!(reg & DW_UART_CPR_DMA_EXTRA)) > > + data->no_dma = 1; > > My question still remains: Does this bit is _guaranteed_ to be set when this IP > is integrated on all possible DMAs? I'll get rid of that entirely, let's just hope there is always DMA support. Thanks, Miquèl
diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c index 88fa17882df5..2f4a818f787c 100644 --- a/drivers/tty/serial/8250/8250_dw.c +++ b/drivers/tty/serial/8250/8250_dw.c @@ -564,8 +564,8 @@ static int dw8250_probe(struct platform_device *pdev) if (!data->skip_autocfg) dw8250_setup_port(p); - /* If we have a valid fifosize, try hooking up DMA */ - if (p->fifosize) { + /* If we have a valid fifosize and DMA support, try hooking up DMA */ + if (p->fifosize && !data->no_dma) { data->data.dma.rxconf.src_maxburst = p->fifosize / 4; data->data.dma.txconf.dst_maxburst = p->fifosize / 4; up->dma = &data->data.dma; diff --git a/drivers/tty/serial/8250/8250_dwlib.c b/drivers/tty/serial/8250/8250_dwlib.c index cef20ca3ad61..b3ff67401670 100644 --- a/drivers/tty/serial/8250/8250_dwlib.c +++ b/drivers/tty/serial/8250/8250_dwlib.c @@ -92,6 +92,8 @@ void dw8250_setup_port(struct uart_port *p) { struct uart_8250_port *up = up_to_u8250p(p); const struct dw8250_platform_data *pdata = device_get_match_data(up->port.dev); + struct dw8250_port_data *d = p->private_data; + struct dw8250_data *data = container_of(d, struct dw8250_data, data); u32 reg; /* @@ -110,8 +112,6 @@ void dw8250_setup_port(struct uart_port *p) dw8250_writel_ext(p, DW_UART_DLF, 0); if (reg) { - struct dw8250_port_data *d = p->private_data; - d->dlf_size = fls(reg); p->get_divisor = dw8250_get_divisor; p->set_divisor = dw8250_set_divisor; @@ -136,5 +136,8 @@ void dw8250_setup_port(struct uart_port *p) if (reg & DW_UART_CPR_SIR_MODE) up->capabilities |= UART_CAP_IRDA; + + if (!(reg & DW_UART_CPR_DMA_EXTRA)) + data->no_dma = 1; } EXPORT_SYMBOL_GPL(dw8250_setup_port); diff --git a/drivers/tty/serial/8250/8250_dwlib.h b/drivers/tty/serial/8250/8250_dwlib.h index 704ba91ab09f..ff965345fc14 100644 --- a/drivers/tty/serial/8250/8250_dwlib.h +++ b/drivers/tty/serial/8250/8250_dwlib.h @@ -39,6 +39,7 @@ struct dw8250_data { unsigned int skip_autocfg:1; unsigned int uart_16550_compatible:1; + unsigned int no_dma:1; }; void dw8250_do_set_termios(struct uart_port *p, struct ktermios *termios, struct ktermios *old);