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Date: Mon, 31 Oct 2016 14:07:58 +1100 (AEDT)
From: Finn Thain <fthain@...egraphics.com.au>
To: Ondrej Zary <linux@...nbow-software.org>
cc: Christoph Hellwig <hch@...radead.org>, linux-scsi@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] NCR5380: Use probe_irq_*() for IRQ probing
On Sun, 30 Oct 2016, Ondrej Zary wrote:
> Use standard probe_irq_on() and probe_irq_off() functions instead of own
> implementation.
Thanks for doing this.
> This prevents warning messages like this in the kernel log:
> genirq: Flags mismatch irq 1. 00000000 (NCR-probe) vs. 00000080 (i8042)
>
> Move the IRQ trigger code to a separate function so it can be used for
> other purposes (testing if the IRQ works).
>
> Also add missing IRQ reset after probe.
>
> Signed-off-by: Ondrej Zary <linux@...nbow-software.org>
> ---
> drivers/scsi/NCR5380.c | 72 +++++++++++++++++-----------------------------
> drivers/scsi/NCR5380.h | 3 +-
> drivers/scsi/g_NCR5380.c | 2 +-
> 3 files changed, 29 insertions(+), 48 deletions(-)
>
> diff --git a/drivers/scsi/NCR5380.c b/drivers/scsi/NCR5380.c
> index d849ffa..01c0027 100644
> --- a/drivers/scsi/NCR5380.c
> +++ b/drivers/scsi/NCR5380.c
> @@ -351,50 +351,13 @@ static void NCR5380_print_phase(struct Scsi_Host *instance)
> }
> #endif
>
> -
> -static int probe_irq;
> -
> -/**
> - * probe_intr - helper for IRQ autoprobe
> - * @irq: interrupt number
> - * @dev_id: unused
> - * @regs: unused
> - *
> - * Set a flag to indicate the IRQ in question was received. This is
> - * used by the IRQ probe code.
> - */
> -
> -static irqreturn_t probe_intr(int irq, void *dev_id)
> -{
> - probe_irq = irq;
> - return IRQ_HANDLED;
> -}
> -
> -/**
> - * NCR5380_probe_irq - find the IRQ of an NCR5380
> - * @instance: NCR5380 controller
> - * @possible: bitmask of ISA IRQ lines
> - *
> - * Autoprobe for the IRQ line used by the NCR5380 by triggering an IRQ
> - * and then looking to see what interrupt actually turned up.
> - */
> -
> -static int __maybe_unused NCR5380_probe_irq(struct Scsi_Host *instance,
> - int possible)
> +static void NCR5380_trigger_irq(struct Scsi_Host *instance)
> {
> struct NCR5380_hostdata *hostdata = shost_priv(instance);
> - unsigned long timeout;
> - int trying_irqs, i, mask;
> -
> - for (trying_irqs = 0, i = 1, mask = 2; i < 16; ++i, mask <<= 1)
> - if ((mask & possible) && (request_irq(i, &probe_intr, 0, "NCR-probe", NULL) == 0))
> - trying_irqs |= mask;
> -
> - timeout = jiffies + msecs_to_jiffies(250);
> - probe_irq = NO_IRQ;
> + unsigned long timeout = jiffies + msecs_to_jiffies(2500);
>
> /*
> - * A interrupt is triggered whenever BSY = false, SEL = true
> + * An interrupt is triggered whenever BSY = false, SEL = true
> * and a bit set in the SELECT_ENABLE_REG is asserted on the
> * SCSI bus.
> *
> @@ -402,23 +365,40 @@ static int __maybe_unused NCR5380_probe_irq(struct Scsi_Host *instance,
> * (I/O, C/D, and MSG) match those in the TCR, so we must reset that
> * to zero.
> */
> -
> NCR5380_write(TARGET_COMMAND_REG, 0);
> NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
> NCR5380_write(OUTPUT_DATA_REG, hostdata->id_mask);
> NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_DATA | ICR_ASSERT_SEL);
>
> - while (probe_irq == NO_IRQ && time_before(jiffies, timeout))
> + while (!(NCR5380_read(BUS_AND_STATUS_REG) & BASR_IRQ) &&
> + time_before(jiffies, timeout))
> schedule_timeout_uninterruptible(1);
You don't need a 2.5 second timeout here. To raise the interrupt the chip
should not need more than a bus settle delay (400ns). Calling msleep(1)
should be plenty.
Better still, please drop the loop, the delay and the BASR_IRQ test here,
and if need be, put the delay in the caller. This routine discards the
result of that sequence anyway.
>
> NCR5380_write(SELECT_ENABLE_REG, 0);
> NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
> +}
>
> - for (i = 1, mask = 2; i < 16; ++i, mask <<= 1)
> - if (trying_irqs & mask)
> - free_irq(i, NULL);
> +/**
> + * NCR5380_probe_irq - find the IRQ of an NCR5380
> + * @instance: NCR5380 controller
> + *
> + * Autoprobe for the IRQ line used by the NCR5380 by triggering an IRQ
> + * and then looking to see what interrupt actually turned up.
> + */
> +
> +static int NCR5380_probe_irq(struct Scsi_Host *instance)
> +{
> + struct NCR5380_hostdata *hostdata = shost_priv(instance);
> + int irqs, irq;
> +
Please rename irqs to irq_mask.
Other drivers like tty/cyclades.c begin with,
/* forget possible initially masked and pending IRQ */
irq = probe_irq_off(probe_irq_on());
Perhaps we need that here too?
> + irqs = probe_irq_on();
You should clear any pending interrupt on the chip before you try to
trigger another one.
> + NCR5380_trigger_irq(instance);
Please do the msleep(1) here.
> + irq = probe_irq_off(irqs);
> + NCR5380_read(RESET_PARITY_INTERRUPT_REG);
> + if (irq < 0)
> + irq = 0;
Please use NO_IRQ instead of 0.
>
> - return probe_irq;
> + return irq;
> }
>
> /**
> diff --git a/drivers/scsi/NCR5380.h b/drivers/scsi/NCR5380.h
> index 3c6ce54..b2fca52 100644
> --- a/drivers/scsi/NCR5380.h
> +++ b/drivers/scsi/NCR5380.h
> @@ -290,7 +290,8 @@ static inline struct scsi_cmnd *NCR5380_to_scmd(struct NCR5380_cmd *ncmd_ptr)
> #define NCR5380_dprint_phase(flg, arg) do {} while (0)
> #endif
>
> -static int NCR5380_probe_irq(struct Scsi_Host *instance, int possible);
> +static void NCR5380_trigger_irq(struct Scsi_Host *instance);
> +static int NCR5380_probe_irq(struct Scsi_Host *instance);
> static int NCR5380_init(struct Scsi_Host *instance, int flags);
> static int NCR5380_maybe_reset_bus(struct Scsi_Host *);
> static void NCR5380_exit(struct Scsi_Host *instance);
Please move NCR5380_probe_irq and NCR5380_trigger_irq implementations and
prototypes out of the core driver and into g_NCR5380.c. The reason is, ISA
cards are probably the only 5380 cards ever likely to need manual IRQ
configuration. It would better to have g_NCR5380 support more ISA cards
than to add more ISA drivers, therefore this code isn't likely to be
needed in the core driver.
Thanks.
--
> diff --git a/drivers/scsi/g_NCR5380.c b/drivers/scsi/g_NCR5380.c
> index 7299ad9..3790ed5 100644
> --- a/drivers/scsi/g_NCR5380.c
> +++ b/drivers/scsi/g_NCR5380.c
> @@ -265,7 +265,7 @@ static int generic_NCR5380_init_one(struct scsi_host_template *tpnt,
> if (irq != IRQ_AUTO)
> instance->irq = irq;
> else
> - instance->irq = NCR5380_probe_irq(instance, 0xffff);
> + instance->irq = NCR5380_probe_irq(instance);
>
> /* Compatibility with documented NCR5380 kernel parameters */
> if (instance->irq == 255)
>
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