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SubjectRe: [PATCH v2 08/22] soc/fsl/qbman_portals: add APIs to retrieve the probing status
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On 2018-10-03 11:50 AM, Laurentiu Tudor wrote:
> Hi Leo,
>
> On 27.09.2018 23:03, Li Yang wrote:
>> On Wed, Sep 26, 2018 at 8:26 AM <laurentiu.tudor@nxp.com> wrote:
>>>
>>> From: Laurentiu Tudor <laurentiu.tudor@nxp.com>
>>>
>>> Add a couple of new APIs to check the probing status of the required
>>> cpu bound qman and bman portals:
>>> 'int bman_portals_probed()' and 'int qman_portals_probed()'.
>>> They return the following values.
>>> * 1 if qman/bman portals were all probed correctly
>>> * 0 if qman/bman portals were not yet probed
>>> * -1 if probing of qman/bman portals failed
>>> Drivers that use qman/bman portal driver services are required to use
>>> these APIs before calling any functions exported by these drivers or
>>> otherwise they will crash the kernel.
>>> First user will be the dpaa1 ethernet driver, coming in a subsequent
>>> patch.
>>>
>>> Signed-off-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
>>> ---
>>> drivers/soc/fsl/qbman/bman_portal.c | 10 ++++++++++
>>> drivers/soc/fsl/qbman/qman_portal.c | 10 ++++++++++
>>> include/soc/fsl/bman.h | 8 ++++++++
>>> include/soc/fsl/qman.h | 9 +++++++++
>>> 4 files changed, 37 insertions(+)
>>>
>>> diff --git a/drivers/soc/fsl/qbman/bman_portal.c b/drivers/soc/fsl/qbman/bman_portal.c
>>> index f9edd28894fd..8048d35de8a2 100644
>>> --- a/drivers/soc/fsl/qbman/bman_portal.c
>>> +++ b/drivers/soc/fsl/qbman/bman_portal.c
>>> @@ -32,6 +32,7 @@
>>>
>>> static struct bman_portal *affine_bportals[NR_CPUS];
>>> static struct cpumask portal_cpus;
>>> +static int __bman_portals_probed;
>>> /* protect bman global registers and global data shared among portals */
>>> static DEFINE_SPINLOCK(bman_lock);
>>>
>>> @@ -85,6 +86,12 @@ static int bman_online_cpu(unsigned int cpu)
>>> return 0;
>>> }
>>>
>>> +int bman_portals_probed(void)
>>> +{
>>> + return __bman_portals_probed;
>>> +}
>>> +EXPORT_SYMBOL_GPL(bman_portals_probed);
>>> +
>>> static int bman_portal_probe(struct platform_device *pdev)
>>> {
>>> struct device *dev = &pdev->dev;
>>> @@ -148,6 +155,7 @@ static int bman_portal_probe(struct platform_device *pdev)
>>> spin_lock(&bman_lock);
>>> cpu = cpumask_next_zero(-1, &portal_cpus);
>>> if (cpu >= nr_cpu_ids) {
>>> + __bman_portals_probed = 1;
>>
>> What if the last CPU is not used for portals? Is there a hard
>> requirement that all CPUs need to be used for portal?
>
> As far as I know, in the current driver design a portal is required for
> each CPU.
>
>> What happens if the last CPU is offline?
>
> Can this happen at probe time?

As I understand things, yes - if you boot with "maxcpus=1", only the
boot CPU will be onlined by the kernel, but the others can still be
brought up manually by userspace later.

Robin.

> Anyway, I'm not sure that the driver is even aware of cpu hotplug but
> I'll let Roy comment on this one.
>
>>
>>> /* unassigned portal, skip init */
>>> spin_unlock(&bman_lock);
>>> return 0;
>>> @@ -173,6 +181,8 @@ static int bman_portal_probe(struct platform_device *pdev)
>>> err_ioremap2:
>>> memunmap(pcfg->addr_virt_ce);
>>> err_ioremap1:
>>> + __bman_portals_probed = 1;
>>> +
>>
>> There are other error paths that not covered.
>
> Right, thanks for pointing. On top of that, the assigned value here
> should be -1 to signal error (instead of 1 which signals success).
>
> ---
> Best Regards, Laurentiu
>

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