[PATCH v3 1/2] Staging: comedi: convert while loops to timeouts in
Chase Southwood
chase.southwood at yahoo.com
Sat Mar 8 01:43:04 UTC 2014
This patch changes a handful of while loops to timeouts to prevent
infinite looping on hardware failure. A couple such loops are in a
function (s626_debi_transfer()) which is called from critical sections,
so comedi_timeout() is unusable for them, and an iterative timeout is
used instead. For the while loops in a context where comedi_timeout() is
allowed, a new callback function, s626_send_dac_eoc(), has been defined
to evaluate the conditions that the while loops are testing. The new
callback employs a switch statement based on a simple new enum so that
it is usable for all of the different conditions tested in while loops
in s626_send_dac(). The proper comedi_timeout() calls are then used.
Signed-off-by: Chase Southwood <chase.southwood at yahoo.com>
---
Ian, here is a version of this patchset employing the enum you recommended.
The second patch has been rebased on top of this one.
2: Used comedi_timeout() where appropriate, introduce callback function
3: Updated callback to switch on new enum.
drivers/staging/comedi/drivers/s626.c | 87 ++++++++++++++++++++++++++++++-----
1 file changed, 75 insertions(+), 12 deletions(-)
diff --git a/drivers/staging/comedi/drivers/s626.c b/drivers/staging/comedi/drivers/s626.c
index 5ba4b4a..ff9dde1 100644
--- a/drivers/staging/comedi/drivers/s626.c
+++ b/drivers/staging/comedi/drivers/s626.c
@@ -209,6 +209,8 @@ static const struct comedi_lrange s626_range_table = {
static void s626_debi_transfer(struct comedi_device *dev)
{
struct s626_private *devpriv = dev->private;
+ static const int timeout = 10000;
+ int i;
/* Initiate upload of shadow RAM to DEBI control register */
s626_mc_enable(dev, S626_MC2_UPLD_DEBI, S626_P_MC2);
@@ -217,12 +219,22 @@ static void s626_debi_transfer(struct comedi_device *dev)
* Wait for completion of upload from shadow RAM to
* DEBI control register.
*/
- while (!s626_mc_test(dev, S626_MC2_UPLD_DEBI, S626_P_MC2))
- ;
+ for (i = 0; i < timeout; i++) {
+ if (s626_mc_test(dev, S626_MC2_UPLD_DEBI, S626_P_MC2))
+ break;
+ udelay(1);
+ }
+ if (i == timeout)
+ comedi_error(dev, "Timeout while uploading to DEBI control register.");
/* Wait until DEBI transfer is done */
- while (readl(devpriv->mmio + S626_P_PSR) & S626_PSR_DEBI_S)
- ;
+ for (i = 0; i < timeout; i++) {
+ if (!(readl(devpriv->mmio + S626_P_PSR) & S626_PSR_DEBI_S))
+ break;
+ udelay(1);
+ }
+ if (i == timeout)
+ comedi_error(dev, "DEBI transfer timeout.");
}
/*
@@ -351,6 +363,48 @@ static const uint8_t s626_trimadrs[] = {
0x40, 0x41, 0x42, 0x50, 0x51, 0x52, 0x53, 0x60, 0x61, 0x62, 0x63
};
+enum {
+ s626_send_dac_wait_not_mc1_a2out,
+ s626_send_dac_wait_ssr_af2_out,
+ s626_send_dac_wait_fb_buffer2_msb_00,
+ s626_send_dac_wait_fb_buffer2_msb_ff
+};
+
+static int s626_send_dac_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_send_dac_wait_not_mc1_a2out:
+ status = readl(devpriv->mmio + S626_P_MC1);
+ if (!(status & S626_MC1_A2OUT))
+ return 0;
+ break;
+ case s626_send_dac_wait_ssr_af2_out:
+ status = readl(devpriv->mmio + S626_P_SSR);
+ if (status & S626_SSR_AF2_OUT)
+ return 0;
+ break;
+ case s626_send_dac_wait_fb_buffer2_msb_00:
+ status = readl(devpriv->mmio + S626_P_FB_BUFFER2);
+ if (!(status & 0xff000000))
+ return 0;
+ break;
+ case s626_send_dac_wait_fb_buffer2_msb_ff:
+ status = readl(devpriv->mmio + S626_P_FB_BUFFER2);
+ if (status & 0xff000000)
+ return 0;
+ break;
+ default:
+ return -EINVAL;
+ }
+ return -EBUSY;
+}
+
/*
* Private helper function: Transmit serial data to DAC via Audio
* channel 2. Assumes: (1) TSL2 slot records initialized, and (2)
@@ -359,6 +413,7 @@ static const uint8_t s626_trimadrs[] = {
static void s626_send_dac(struct comedi_device *dev, uint32_t val)
{
struct s626_private *devpriv = dev->private;
+ int ret;
/* START THE SERIAL CLOCK RUNNING ------------- */
@@ -404,8 +459,10 @@ static void s626_send_dac(struct comedi_device *dev, uint32_t val)
* Done by polling the DMAC enable flag; this flag is automatically
* cleared when the transfer has finished.
*/
- while (readl(devpriv->mmio + S626_P_MC1) & S626_MC1_A2OUT)
- ;
+ ret = comedi_timeout(dev, NULL, NULL, s626_send_dac_eoc,
+ s626_send_dac_wait_not_mc1_a2out);
+ if (ret)
+ comedi_error(dev, "DMA transfer timeout.");
/* START THE OUTPUT STREAM TO THE TARGET DAC -------------------- */
@@ -425,8 +482,10 @@ static void s626_send_dac(struct comedi_device *dev, uint32_t val)
* finished transferring the DAC's data DWORD from the output FIFO
* to the output buffer register.
*/
- while (!(readl(devpriv->mmio + S626_P_SSR) & S626_SSR_AF2_OUT))
- ;
+ ret = comedi_timeout(dev, NULL, NULL, s626_send_dac_eoc,
+ s626_send_dac_wait_ssr_af2_out);
+ if (ret)
+ comedi_error(dev, "TSL timeout waiting for slot 1 to execute.");
/*
* Set up to trap execution at slot 0 when the TSL sequencer cycles
@@ -466,8 +525,10 @@ static void s626_send_dac(struct comedi_device *dev, uint32_t val)
* from 0xFF to 0x00, which slot 0 causes to happen by shifting
* out/in on SD2 the 0x00 that is always referenced by slot 5.
*/
- while (readl(devpriv->mmio + S626_P_FB_BUFFER2) & 0xff000000)
- ;
+ ret = comedi_timeout(dev, NULL, NULL, s626_send_dac_eoc,
+ s626_send_dac_wait_fb_buffer2_msb_00);
+ if (ret)
+ comedi_error(dev, "TSL timeout waiting for slot 0 to execute.");
}
/*
* Either (1) we were too late setting the slot 0 trap; the TSL
@@ -486,8 +547,10 @@ static void s626_send_dac(struct comedi_device *dev, uint32_t val)
* the next DAC write. This is detected when FB_BUFFER2 MSB changes
* from 0x00 to 0xFF.
*/
- while (!(readl(devpriv->mmio + S626_P_FB_BUFFER2) & 0xff000000))
- ;
+ ret = comedi_timeout(dev, NULL, NULL, s626_send_dac_eoc,
+ s626_send_dac_wait_fb_buffer2_msb_ff);
+ if (ret)
+ comedi_error(dev, "TSL timeout waiting for slot 0 to execute.");
}
/*
--
1.8.5.3
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