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Date: Fri, 12 Nov 2010 10:07:28 +0000
From: Alan Cox <alan@...rguk.ukuu.org.uk>
To: Tomoya MORINAGA <tomoya-linux@....okisemi.com>
Cc: Alan Cox <alan@...ux.intel.com>,
Greg Kroah-Hartman <gregkh@...e.de>,
Ben Dooks <ben-linux@...ff.org>,
Kukjin Kim <kgene.kim@...sung.com>,
Mike Frysinger <vapier@...too.org>,
Feng Tang <feng.tang@...el.com>,
Tobias Klauser <tklauser@...tanz.ch>,
linux-kernel@...r.kernel.org, yong.y.wang@...el.com,
qi.wang@...el.com, kok.howg.ewe@...el.com,
andrew.chih.howe.khor@...el.com
Subject: Re: [PATCH v2] EG20T: Update PCH_UART driver to 2.6.36
On Fri, 12 Nov 2010 11:55:42 +0900
Tomoya MORINAGA <tomoya-linux@....okisemi.com> wrote:
> Hi Alan,
>
> I have modified for your indications.
> (As to details, please refer previous my response mail)
> Please check below.
Thanks.. More comments below
I have looked at the locking and agree it looks right.
+#include <linux/interrupt.h>
+#include <linux/io.h>
+
+#ifdef CONFIG_PCH_DMA
+#include <linux/dmaengine.h>
+#include <linux/pch_dma.h>
+#endif
You do not need this ifdef. Even if you are not using the DMA feature it
will still compile. DMA/non-DMA needs to be runtime. See below
+enum {
+ PCH_UART_HAL_INVALID_PARAM = EINVAL,
+ PCH_UART_HAL_NOT_INITIALIZED = 256,
+ PCH_UART_HAL_NOT_REQUESTED,
+ PCH_UART_HAL_BASE_NOT_SET,
+ PCH_UART_HAL_INVALID_BAUD,
+ PCH_UART_HAL_INVALID_PARITY,
+ PCH_UART_HAL_INVALID_WLS,
+ PCH_UART_HAL_INVALID_FIFO_CLR,
+ PCH_UART_HAL_INVALID_DMAMODE,
+ PCH_UART_HAL_INVALID_FIFOSIZE,
+ PCH_UART_HAL_INVALID_TRIGGER,
+ PCH_UART_HAL_INVALID_STB,
+ PCH_UART_HAL_READ_ERROR,
+};
These should be replaced with ordinary Linux error codes in the functions.
+struct eg20t_port {
+ struct uart_port port;
+ int port_type;
+ void __iomem *membase;
+ resource_size_t mapbase;
+ unsigned int iobase;
+ struct pci_dev *pdev;
+ int fifo_size;
+ int base_baud;
+ int start_tx;
+ int start_rx;
+ int tx_empty;
+ int int_dis_flag;
+ int trigger;
+ int trigger_level;
+ struct pch_uart_buffer rxbuf;
+ unsigned int dmsr;
+ unsigned int fcr;
+#ifdef CONFIG_PCH_DMA
+ struct dma_async_tx_descriptor *desc_tx;
+ struct dma_async_tx_descriptor *desc_rx;
+ struct pch_dma_slave param_tx;
+ struct pch_dma_slave param_rx;
+ struct dma_chan *chan_tx;
+ struct dma_chan *chan_rx;
+ struct scatterlist sg_tx;
+ struct scatterlist sg_rx;
+ int tx_dma_use;
+ void *rx_buf_virt;
+ dma_addr_t rx_buf_dma;
+#endif
+};
+static unsigned int get_msr(struct eg20t_port *priv, void __iomem *base)
+{
+ unsigned int msr = ioread8(base + PCH_UART_MSR);
+ priv->dmsr |= msr & PCH_UART_MSR_DELTA;
+
+ return msr;
msr should be a u8 ? Is there a reason priv->dmsr is unsigned int ?
+static void pch_uart_hal_enable_interrupt(struct eg20t_port *priv,
+ unsigned int flag)
+{
+ unsigned int ier = ioread8(priv->membase + PCH_UART_IER);
+ ier |= flag & PCH_UART_IER_MASK;
+ iowrite8(ier, priv->membase + PCH_UART_IER);
+}
Same for ier and fcr ?
+static int pch_uart_hal_read(struct eg20t_port *priv, unsigned char *buf,
+ int rx_size)
+{
+ int i;
+ unsigned int rbr, lsr;
+
+ lsr = ioread8(priv->membase + PCH_UART_LSR);
+ for (i = 0, lsr = ioread8(priv->membase + PCH_UART_LSR);
+ i < rx_size && lsr & PCH_UART_LSR_DR;
+ lsr = ioread8(priv->membase + PCH_UART_LSR)) {
+ rbr = ioread8(priv->membase + PCH_UART_RBR);
+ buf[i++] = (unsigned char)rbr;
+ }
Same again here - which would also lose the cast
+static int pch_uart_hal_get_line_status(struct eg20t_port *priv)
+{
+ unsigned int lsr;
+ int ret;
+
+ lsr = ioread8(priv->membase + PCH_UART_LSR);
+ ret = (int)lsr;
And here
+static int push_rx(struct eg20t_port *priv, const unsigned char *buf,
+ int size)
+{
+ struct uart_port *port;
+ struct tty_struct *tty;
+ int sz, i, j;
+ int loop;
+ int pushed;
+
+ port = &priv->port;
+ tty = tty_port_tty_get(&port->state->port);
+ if (!tty) {
+ pr_info("%s:tty is busy now", __func__);
+ return -EBUSY;
+ }
Don't log this. It is a perfectly normal situation - no pr_info needed
(pr_debug if testing perhaps)
+
+ for (pushed = 0, i = 0, loop = 1; (pushed < size) && loop;
+ pushed += sz, i++) {
+ sz = tty_insert_flip_string(tty, &buf[pushed], size - pushed);
+ for (j = 0; (j < 100000) && (sz == 0); j++) {
+ tty_flip_buffer_push(tty);
+ sz = tty_insert_flip_string(tty, &buf[pushed],
+ size - pushed);
+ }
+ if (sz == 0)
+ loop = 0;
+ }
This should not be needed. tty_insert_flip_string tries to insert as much as
it can. Except when tty->low_latency is set, which requires the call is not
from an interrupt handler the flip_buffer_push will queue data to the line
discipline it will not make space.
+ room = tty_buffer_request_room(tty, size);
+
+ if (room < size)
+ dev_warn(port->dev, "Rx overrun: dropping %u bytes\n",
+ size - room);
+ if (!room)
+ return room;
+
+ for (i = 0; i < room; i++) {
+ tty_insert_flip_char(tty, ((u8 *)sg_virt(&priv->sg_rx))[i],
+ TTY_NORMAL);
+ }
You can replace all of that with a single call to tty_insert_flip_string ?
+ struct tty_struct *tty = tty_port_tty_get(&port->state->port);
+ if (!tty) {
+ pr_info("%s:tty is busy now", __func__);
Again don't log this.
+static void pch_uart_send_xchar(struct uart_port *port, char ch)
+{
+}
??
+ ret = pch_uart_hal_set_fifo(priv, PCH_UART_HAL_DMA_MODE0,
+ fifo_size, priv->trigger);
Is this missing check intentional ?
+
+ ret = request_irq(priv->port.irq, pch_uart_interrupt, IRQF_SHARED,
+ KBUILD_MODNAME, priv);
+
+ if (ret < 0)
+ return ret;
+static int pch_uart_verify_port(struct uart_port *port,
+ struct serial_struct *serinfo)
+{
+ return 0;
+}
As you don't support low latency you want to do
static int pch_uart_verify_port(struct uart_port *port,
struct serial_struct *serinfo)
{
if (serinfo->flags & UPF_LOW_LATENCY)
return -EOPNOTSUPP;
return 0;
}
(A few other drivers also miss this)
What you could also consider doing is
static int pch_uart_verify_port(struct uart_port *port,
struct serial_struct *serinfo)
{
if (serinfo->flags & UPF_LOW_LATENCY)
use_pio_modes;
/* Avoid tty->low_latency being set as we do not support it */
serinfo->flags &= ~UPF_LOW_LATENCY;
} else
use_dma_modes;
return 0;
}
I think that would make "setserial /dev/ttyPCH0 low_latency" select PIO
and the reverse "setserial /dev/ttyPCH0 ^low_latency" select DMA mode but it
would need testing to make sure that it is all that is needed.
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