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Date: Tue, 12 Dec 2017 04:55:47 +0000
From: Bharat Bhushan <bharat.bhushan@....com>
To: Nipun Gupta <nipun.gupta@....com>,
Laurentiu Tudor <laurentiu.tudor@....com>,
"stuyoder@...il.com" <stuyoder@...il.com>,
"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
"cakturk@...il.com" <cakturk@...il.com>,
"bretth256@...il.com" <bretth256@...il.com>,
"arnd@...db.de" <arnd@...db.de>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>,
Nipun Gupta <nipun.gupta@....com>
Subject: RE: [RESEND PATCH 1/2 v2] staging: fsl-mc: Allocate IRQ's before
scanning DPRC objects
> -----Original Message-----
> From: Nipun Gupta [mailto:nipun.gupta@....com]
> Sent: Monday, December 11, 2017 9:16 PM
> To: Laurentiu Tudor <laurentiu.tudor@....com>; stuyoder@...il.com;
> Bharat Bhushan <bharat.bhushan@....com>; gregkh@...uxfoundation.org;
> cakturk@...il.com; bretth256@...il.com; arnd@...db.de
> Cc: linux-kernel@...r.kernel.org; devel@...verdev.osuosl.org; Nipun Gupta
> <nipun.gupta@....com>
> 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@....com>
Looks ok to me,
Reviewed-by: Bharat Bhushan <bharat.bhushan@....com>
> ---
> 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
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