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Date: Tue, 25 Mar 2014 12:11:59 +0000
From: Ian Abbott <abbotti@....co.uk>
To: Chase Southwood <chase.southwood@...oo.com>,
gregkh@...uxfoundation.org
CC: hsweeten@...ionengravers.com, devel@...verdev.osuosl.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: comedi: s626: use comedi_timeout() on remaining
loops
On 2014-03-25 05:09, Chase Southwood wrote:
> There were just a handful of more while loops in this file that need timeouts,
> and this patch takes care of them, using comedi_timeout(). A couple of new
> callbacks are introduced, but there was one case where the appropriate callback
> function was already defined; in this case I have just used that.
>
> Signed-off-by: Chase Southwood <chase.southwood@...oo.com>
I think it can be simplified a bit as described below.
> ---
> drivers/staging/comedi/drivers/s626.c | 66 ++++++++++++++++++++++++++++++-----
> 1 file changed, 58 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/staging/comedi/drivers/s626.c b/drivers/staging/comedi/drivers/s626.c
> index 95fadf3..4dc5659 100644
> --- a/drivers/staging/comedi/drivers/s626.c
> +++ b/drivers/staging/comedi/drivers/s626.c
> @@ -295,10 +295,24 @@ static void s626_debi_replace(struct comedi_device *dev, unsigned int addr,
>
> /* ************** EEPROM ACCESS FUNCTIONS ************** */
>
> +static int s626_i2c_handshake_eoc(struct comedi_device *dev,
> + struct comedi_subdevice *s,
> + struct comedi_insn *insn,
> + unsigned long context)
> +{
> + unsigned int status;
> +
> + status = s626_mc_test(dev, S626_MC2_UPLD_IIC, S626_P_MC2);
> + if (status)
> + return 0;
> + return -EBUSY;
> +}
> +
So s626_i2c_handshake_eoc() tests the S626_MC2_UPLD_IIC bit of the
S626_P_MC2 register and returns 0 if the bit is high or -EBUSY if it is low.
> static uint32_t s626_i2c_handshake(struct comedi_device *dev, uint32_t val)
> {
> struct s626_private *devpriv = dev->private;
> unsigned int ctrl;
> + uint32_t ret;
>
> /* Write I2C command to I2C Transfer Control shadow register */
> writel(val, devpriv->mmio + S626_P_I2CCTRL);
> @@ -308,8 +322,9 @@ static uint32_t s626_i2c_handshake(struct comedi_device *dev, uint32_t val)
> * wait for upload confirmation.
> */
> s626_mc_enable(dev, S626_MC2_UPLD_IIC, S626_P_MC2);
> - while (!s626_mc_test(dev, S626_MC2_UPLD_IIC, S626_P_MC2))
> - ;
> + ret = comedi_timeout(dev, NULL, NULL, s626_i2c_handshake_eoc, 0);
> + if (ret)
> + return ret;
That's fine. Both the original while loop and the comedi_timeout() call
are waiting for the S626_MC_UPLD_IIC bit to go high.
>
> /* Wait until I2C bus transfer is finished or an error occurs */
> do {
> @@ -2029,8 +2044,9 @@ static int s626_ai_insn_read(struct comedi_device *dev,
> /* Wait for the data to arrive in FB BUFFER 1 register. */
>
> /* Wait for ADC done */
> - while (!(readl(devpriv->mmio + S626_P_PSR) & S626_PSR_GPIO2))
> - ;
> + ret = comedi_timeout(dev, s, insn, s626_ai_eoc, 0);
> + if (ret)
> + return ret;
>
> /* Fetch ADC data from audio interface's input shift register. */
>
> @@ -2641,6 +2657,36 @@ static int s626_allocate_dma_buffers(struct comedi_device *dev)
> return 0;
> }
>
> +enum {
> + s626_initialize_wait_i2c_abort,
> + s626_initialize_wait_i2c_err_reset
> +};
> +
> +static int s626_initialize_eoc(struct comedi_device *dev,
> + struct comedi_subdevice *s,
> + struct comedi_insn *insn,
> + unsigned long context)
> +{
> + struct s626_private *devpriv = dev->private;
> + unsigned int status;
> +
> + switch (context) {
> + case s626_initialize_wait_i2c_abort:
> + status = readl(devpriv->mmio + S626_P_MC2);
> + if (status & S626_MC2_UPLD_IIC)
> + return 0;
> + break;
The 's626_initialize_wait_i2c_abort' case returns 0 if the
S626_MC2_UPLD_IIC bit is high and the function around it will return
-EBUSY otherwise. That's basically the same as the
s626_i2c_handshake_eoc() callback except it doesn't call s626_mc_test()
to read the register and check the bit, it does it itself.
> + case s626_initialize_wait_i2c_err_reset:
> + status = s626_mc_test(dev, S626_MC2_UPLD_IIC, S626_P_MC2);
> + if (status)
> + return 0;
> + break;
The 's626_initialize_wait_i2c_err_reset' case is also basically the same
as the s626_i2c_handshake_eoc() callback.
> + default:
> + return -EINVAL;
> + }
> + return -EBUSY;
> +}
> +
It seems both supported context case values of the s626_initialize_eoc()
callback basically do the same thing as the s626_i2c_handshake_eoc()
callback, so you could use that callback instead of this one.
> static int s626_initialize(struct comedi_device *dev)
> {
> struct s626_private *devpriv = dev->private;
> @@ -2681,8 +2727,10 @@ static int s626_initialize(struct comedi_device *dev)
> writel(S626_I2C_CLKSEL | S626_I2C_ABORT,
> devpriv->mmio + S626_P_I2CSTAT);
> s626_mc_enable(dev, S626_MC2_UPLD_IIC, S626_P_MC2);
> - while (!(readl(devpriv->mmio + S626_P_MC2) & S626_MC2_UPLD_IIC))
> - ;
> + ret = comedi_timeout(dev, NULL, NULL, s626_initialize_eoc,
> + s626_initialize_wait_i2c_abort);
> + if (ret)
> + return ret;
That's fine. The original while loop is waiting for the
S626_MC2_UPLD_IIC bit to go high and so is the comedi_timeout() call.
But you could re-use the s626_i2c_handshake_eoc() callback instead of
the s626_initialize_wait_i2c_abort() as described above.
>
> /*
> * Per SAA7146 data sheet, write to STATUS
> @@ -2691,8 +2739,10 @@ static int s626_initialize(struct comedi_device *dev)
> for (i = 0; i < 2; i++) {
> writel(S626_I2C_CLKSEL, devpriv->mmio + S626_P_I2CSTAT);
> s626_mc_enable(dev, S626_MC2_UPLD_IIC, S626_P_MC2);
> - while (!s626_mc_test(dev, S626_MC2_UPLD_IIC, S626_P_MC2))
> - ;
> + ret = comedi_timeout(dev, NULL, NULL, s626_initialize_eoc,
> + s626_initialize_wait_i2c_err_reset);
> + if (ret)
> + return ret;
As above, the original while loop is waiting for the S626_MC2_UPLD_IIC
bit to go high, so you could re-use the s626_i2c_handshake_eoc() callback.
> }
>
> /*
>
Best regards,
Ian.
--
-=( Ian Abbott @ MEV Ltd. E-mail: <abbotti@....co.uk> )=-
-=( Tel: +44 (0)161 477 1898 FAX: +44 (0)161 718 3587 )=-
--
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