RE: [RESEND PATCH 1/2 v2] staging: fsl-mc: Allocate IRQ's before scanning DPRC objects

[Bharat Bhushan]

> -----Original Message-----
> From: Nipun Gupta [mailto:nipun.gupta@xxxxxxx]
> Sent: Monday, December 11, 2017 9:16 PM
> To: Laurentiu Tudor <laurentiu.tudor@xxxxxxx>; stuyoder@xxxxxxxxx;
> Bharat Bhushan <bharat.bhushan@xxxxxxx>; gregkh@xxxxxxxxxxxxxxxxxxx;
> cakturk@xxxxxxxxx; bretth256@xxxxxxxxx; arnd@xxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx; devel@xxxxxxxxxxxxxxxxxxxx; Nipun Gupta
> <nipun.gupta@xxxxxxx>
> Subject: [RESEND PATCH 1/2 v2] staging: fsl-mc: Allocate IRQ's before
> scanning DPRC objects
> 
> Following is the current scenario when the devices are probed:
> 
>   FSL_MC Bus probe ---> dprc probe ---> dprc devices scan --->
>     probe devices in DPRC container ---> allocate IRQ's
> 
> In case the devices being probed in the DPRC container need the IRQ's;
> probing of that device will fail.
> 
> In current scenario the devices which need IRQ's such as DPIO gets deferred
> because they aren't registered when first time the probing of these devices
> is done in the dprc scan.
> So they are probed once IRQ's have been allocated.
> 
> In case where DPRC probing itself gets deferred, which does in case IOMMU
> is enabled; all the devices in DPRC container gets probed before IRQ's are
> allocated. This causes devices using IRQ's (such as DPIO) to fail.
> 
> So having IRQ's allocated before any of the devices in the DPRC container are
> probed is more legitimate.
> 
> After this patch following is the flow of execution:
> 
>   FSL_MC Bus probe ---> dprc probe ---> dprc devices scan --->
>     allocate IRQ's ---> probe of devices in DPRC container.
> 
> Signed-off-by: Nipun Gupta <nipun.gupta@xxxxxxx>

Looks ok to me,

Reviewed-by: Bharat Bhushan <bharat.bhushan@xxxxxxx>

> ---
> Resending v2 as missed mentioning the changes in the version Changes in v2:
>   - Polished the commit message
>   - Minor updation in the comment added in the code 'Allocate IRQ's...'
> 
>  drivers/staging/fsl-mc/bus/dprc-driver.c | 49 ++++++++++++++++++---------
> -----
>  1 file changed, 27 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/staging/fsl-mc/bus/dprc-driver.c b/drivers/staging/fsl-
> mc/bus/dprc-driver.c
> index 06df528..f4bde58 100644
> --- a/drivers/staging/fsl-mc/bus/dprc-driver.c
> +++ b/drivers/staging/fsl-mc/bus/dprc-driver.c
> @@ -206,7 +206,8 @@ static void dprc_add_new_devices(struct
> fsl_mc_device *mc_bus_dev,
>   * dprc_scan_objects - Discover objects in a DPRC
>   *
>   * @mc_bus_dev: pointer to the fsl-mc device that represents a DPRC object
> - * @total_irq_count: total number of IRQs needed by objects in the DPRC.
> + * @total_irq_count: If argument is provided the function populates the
> + * total number of IRQs created by objects in the DPRC.
>   *
>   * Detects objects added and removed from a DPRC and synchronizes the
>   * state of the Linux bus driver, MC by adding and removing @@ -228,6
> +229,7 @@ static int dprc_scan_objects(struct fsl_mc_device *mc_bus_dev,
>  	int error;
>  	unsigned int irq_count = mc_bus_dev->obj_desc.irq_count;
>  	struct fsl_mc_obj_desc *child_obj_desc_array = NULL;
> +	struct fsl_mc_bus *mc_bus = to_fsl_mc_bus(mc_bus_dev);
> 
>  	error = dprc_get_obj_count(mc_bus_dev->mc_io,
>  				   0,
> @@ -297,7 +299,26 @@ static int dprc_scan_objects(struct fsl_mc_device
> *mc_bus_dev,
>  		}
>  	}
> 
> -	*total_irq_count = irq_count;
> +	/*
> +	 * Allocate IRQ's before binding the scanned devices with their
> +	 * respective drivers.
> +	 */
> +	if (dev_get_msi_domain(&mc_bus_dev->dev) && !mc_bus-
> >irq_resources) {
> +		if (irq_count > FSL_MC_IRQ_POOL_MAX_TOTAL_IRQS) {
> +			dev_warn(&mc_bus_dev->dev,
> +				 "IRQs needed (%u) exceed IRQs preallocated
> (%u)\n",
> +				 irq_count,
> FSL_MC_IRQ_POOL_MAX_TOTAL_IRQS);
> +		}
> +
> +		error = fsl_mc_populate_irq_pool(mc_bus,
> +				FSL_MC_IRQ_POOL_MAX_TOTAL_IRQS);
> +		if (error < 0)
> +			return error;
> +	}
> +
> +	if (total_irq_count)
> +		*total_irq_count = irq_count;
> +
>  	dprc_remove_devices(mc_bus_dev, child_obj_desc_array,
>  			    num_child_objects);
> 
> @@ -322,7 +343,6 @@ static int dprc_scan_objects(struct fsl_mc_device
> *mc_bus_dev,  static int dprc_scan_container(struct fsl_mc_device
> *mc_bus_dev)  {
>  	int error;
> -	unsigned int irq_count;
>  	struct fsl_mc_bus *mc_bus = to_fsl_mc_bus(mc_bus_dev);
> 
>  	fsl_mc_init_all_resource_pools(mc_bus_dev);
> @@ -331,29 +351,14 @@ static int dprc_scan_container(struct fsl_mc_device
> *mc_bus_dev)
>  	 * Discover objects in the DPRC:
>  	 */
>  	mutex_lock(&mc_bus->scan_mutex);
> -	error = dprc_scan_objects(mc_bus_dev, &irq_count);
> +	error = dprc_scan_objects(mc_bus_dev, NULL);
>  	mutex_unlock(&mc_bus->scan_mutex);
> -	if (error < 0)
> -		goto error;
> -
> -	if (dev_get_msi_domain(&mc_bus_dev->dev) && !mc_bus-
> >irq_resources) {
> -		if (irq_count > FSL_MC_IRQ_POOL_MAX_TOTAL_IRQS) {
> -			dev_warn(&mc_bus_dev->dev,
> -				 "IRQs needed (%u) exceed IRQs preallocated
> (%u)\n",
> -				 irq_count,
> FSL_MC_IRQ_POOL_MAX_TOTAL_IRQS);
> -		}
> -
> -		error = fsl_mc_populate_irq_pool(
> -				mc_bus,
> -				FSL_MC_IRQ_POOL_MAX_TOTAL_IRQS);
> -		if (error < 0)
> -			goto error;
> +	if (error < 0) {
> +		fsl_mc_cleanup_all_resource_pools(mc_bus_dev);
> +		return error;
>  	}
> 
>  	return 0;
> -error:
> -	fsl_mc_cleanup_all_resource_pools(mc_bus_dev);
> -	return error;
>  }
> 
>  /**
> --
> 1.9.1