Date:   Wed, 2 Nov 2016 18:45:04 +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 1/6] NCR5380: Use probe_irq_*() for IRQ probing


On Mon, 31 Oct 2016, Ondrej Zary wrote:

> Use standard probe_irq_on() and probe_irq_off() functions instead of own 
> implementation. 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) and move the code from NCR5380 
> to g_NCR5380.
> 
> Also add missing IRQ reset before and after the probe.
> 
> Signed-off-by: Ondrej Zary <linux@...nbow-software.org>
> ---
>  drivers/scsi/NCR5380.c   |   77 +---------------------------------------------
>  drivers/scsi/NCR5380.h   |    1 -
>  drivers/scsi/g_NCR5380.c |   50 +++++++++++++++++++++++++++++-
>  3 files changed, 50 insertions(+), 78 deletions(-)
> 
> diff --git a/drivers/scsi/NCR5380.c b/drivers/scsi/NCR5380.c
> index d849ffa..4f5ca79 100644
> --- a/drivers/scsi/NCR5380.c
> +++ b/drivers/scsi/NCR5380.c
> @@ -97,9 +97,6 @@
>   * and macros and include this file in your driver.
>   *
>   * These macros control options :
> - * AUTOPROBE_IRQ - if defined, the NCR5380_probe_irq() function will be
> - * defined.
> - *
>   * AUTOSENSE - if defined, REQUEST SENSE will be performed automatically
>   * for commands that return with a CHECK CONDITION status.
>   *
> @@ -127,9 +124,7 @@
>   * NCR5380_dma_residual   - residual byte count
>   *
>   * The generic driver is initialized by calling NCR5380_init(instance),
> - * after setting the appropriate host specific fields and ID.  If the
> - * driver wishes to autoprobe for an IRQ line, the NCR5380_probe_irq(instance,
> - * possible) function may be used.
> + * after setting the appropriate host specific fields and ID.
>   */
>  
>  #ifndef NCR5380_io_delay
> @@ -351,76 +346,6 @@ 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)
> -{
> -	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;
> -
> -	/*
> -	 * A interrupt is triggered whenever BSY = false, SEL = true
> -	 * and a bit set in the SELECT_ENABLE_REG is asserted on the
> -	 * SCSI bus.
> -	 *
> -	 * Note that the bus is only driven when the phase control signals
> -	 * (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))
> -		schedule_timeout_uninterruptible(1);
> -
> -	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);
> -
> -	return probe_irq;
> -}
> -
>  /**
>   * NCR58380_info - report driver and host information
>   * @instance: relevant scsi host instance
> diff --git a/drivers/scsi/NCR5380.h b/drivers/scsi/NCR5380.h
> index 3c6ce54..4724558 100644
> --- a/drivers/scsi/NCR5380.h
> +++ b/drivers/scsi/NCR5380.h
> @@ -290,7 +290,6 @@ 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 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);
> diff --git a/drivers/scsi/g_NCR5380.c b/drivers/scsi/g_NCR5380.c
> index 7299ad9..09c660b 100644
> --- a/drivers/scsi/g_NCR5380.c
> +++ b/drivers/scsi/g_NCR5380.c
> @@ -67,6 +67,54 @@
>  MODULE_ALIAS("g_NCR5380_mmio");
>  MODULE_LICENSE("GPL");
>  
> +static void NCR5380_trigger_irq(struct Scsi_Host *instance)

That should be 'g_NCR5380_trigger_irq' (if it needs a prefix).

> +{
> +	struct NCR5380_hostdata *hostdata = shost_priv(instance);
> +
> +	/*
> +	 * An interrupt is triggered whenever BSY = false, SEL = true
> +	 * and a bit set in the SELECT_ENABLE_REG is asserted on the
> +	 * SCSI bus.
> +	 *
> +	 * Note that the bus is only driven when the phase control signals
> +	 * (I/O, C/D, and MSG) match those in the TCR, so we must reset that
> +	 * to zero.
> +	 */
> +	NCR5380_write(TARGET_COMMAND_REG, 0);

That assumes bus free phase, which we hope is the case but 
NCR5380_maybe_reset_bus() doesn't guarantee it. This is more robust:

	 * Note that the bus is only driven when the phase control signals
	 * (I/O, C/D, and MSG) match those in the TCR.
	 */
	NCR5380_write(TARGET_COMMAND_REG,
		PHASE_SR_TO_TCR(NCR5380_read(STATUS_REG) & PHASE_MASK));


> +	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);
> +
> +	usleep_range(1000, 20000);

Again, msleep(1) would be more appropriate here.

> +
> +	NCR5380_write(SELECT_ENABLE_REG, 0);
> +	NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
> +}
> +
> +/**
> + * NCR5380_probe_irq	-	find the IRQ of an NCR5380

This should be 'g_NCR5380_probe_irq' (if it needs a prefix).

> + * @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 irq_mask, irq;
> +
> +	NCR5380_read(RESET_PARITY_INTERRUPT_REG);
> +	irq_mask = probe_irq_on();
> +	NCR5380_trigger_irq(instance);
> +	irq = probe_irq_off(irq_mask);
> +	NCR5380_read(RESET_PARITY_INTERRUPT_REG);
> +	if (irq < 0)
> +		irq = NO_IRQ;
> +
> +	return irq;
> +}
> +
>  /*
>   * Configure I/O address of 53C400A or DTC436 by writing magic numbers
>   * to ports 0x779 and 0x379.
> @@ -265,7 +313,7 @@ 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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