Re: [Xen-devel] [XEN/ARM PATCH v6 1/1] Add OdroidXU board (Exynos 5410)

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2014-09-11 at 06:30 -0700, Suriyan Ramasami wrote:
> On Thu, Sep 11, 2014 at 5:58 AM, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> > On Wed, 2014-09-10 at 20:35 -0700, Suriyan Ramasami wrote:
> >> On Wed, Sep 10, 2014 at 6:03 PM, Julien Grall <julien.grall@xxxxxxxxxx> 
> >> wrote:
> >> > Hi Suriyan,
> >> >
> >> > On 10/09/14 17:51, Suriyan Ramasami wrote:
> >> >>
> >> >> On Wed, Sep 10, 2014 at 3:21 PM, Julien Grall <julien.grall@xxxxxxxxxx>
> >> >> wrote:
> >> >>>
> >> >>> On 08/09/14 10:26, Suriyan Ramasami wrote:
> >> >>>>
> >> >>>>
> >> >>>> As can be seen, the secondary CPUs check _hotplug_addr for a non zero
> >> >>>> value on first being powered on, or after woken up from a wfe. This
> >> >>>> _hotplug_addr happens to be at offset +0x1c from NS_RAM_BASE.
> >> >>>> Linux mainline too has this hardcoded +0x1c.
> >> >>>
> >> >>>
> >> >>>
> >> >>> You half read the Linux code... This offset is only add when there is a
> >> >>> secure firmware (detected by "samsung,secure-firmware" node in the 
> >> >>> device
> >> >>> tree).
> >> >>>
> >> >>> On the Arndale the node doesn't exist.
> >> >>>
> >> >> Thanks for digging there Julien. Previously, I must have gone through
> >> >> the linux code with only exynos5410 in mind. Nonetheless, looks like I
> >> >> have left out the code which handles the arndale and possibly 5420 and
> >> >> the 5800 (if they do not have "samsung,secure-firmware" defined). But
> >> >> on the other hand, I do see arndale-octa has the "secure-firmware"
> >> >> entry which is a 5420 (so does the 5800). This adds to the confusion.
> >> >> This is from looking at the linux-3.16.y source.
> >> >>
> >> >> Nonetheless, I think to handle arndale for now, I should add the
> >> >> "samsung,secure-firmware" logic in the code which will then use
> >> >> sysram_base_addr instead without any offset.
> >> >>
> >> >> So, how do I go about this? Should I roll out another patch with these
> >> >> cumulative changes and also add the BUG_ON change?
> >> >
> >> >
> >> > I think you could avoid to check the "samsung,secure-firmware" logic by 
> >> > only
> >> > replicate arch/arm/mach-exynos/platsmp.c to Xen.
> >> >
> >>
> >> Hi Julien,
> >>    I think "samsung,secure-firmware" is what differentiates the code
> >> path in platsmp.c, from what I can tell. Correct me if I am wrong,
> >> please. This is from the smp_init's perspective in XEN.
> >>
> >> The code in linux is:
> >>                 /*
> >>                  * Try to set boot address using firmware first
> >>                  * and fall back to boot register if it fails.
> >>                  */
> >>                 ret = call_firmware_op(set_cpu_boot_addr, phys_cpu, 
> >> boot_addr);
> >>                 if (ret && ret != -ENOSYS)
> >>                         goto fail;
> >>                 if (ret == -ENOSYS) {
> >>                         void __iomem *boot_reg = cpu_boot_reg(phys_cpu);
> >>
> >>                         if (IS_ERR(boot_reg)) {
> >>                                 ret = PTR_ERR(boot_reg);
> >>                                 goto fail;
> >>                         }
> >>                         __raw_writel(boot_addr, cpu_boot_reg(phys_cpu));
> >>                 }
> >>
> >> call_firmware_op(set_cpu_boot_addr, ...) will return -ENOSYS (which
> >> then uses the alternative code path of using cpu_boot_reg(), which
> >> uses sysram_base_addr), only if register_firmware_ops() is not called
> >> with &exynos_firmware_ops, as per the code in mach-exynos/firmware.c.
> >> Furthermore, it is not registered in exynos_firmware_init() only if
> >> "samsung,secure-firmware" is not found in the DT.
> >>
> >> I am just wondering, if you had something else in mind which can be
> >> achieved without depending on "samsung,secure-firmware". Please let me
> >> know the alternative.
> >
> > I think what you suggest sounds plausible. For me the following fixes
> > boot on my arndale (I mistakenly thought that it worked earlier but I
> > was testing the wrong thing). If the presence of samsung,secure-firmware
> > is the way to distinguish the two cases then lets go that way.
> >
> 
> Hi Ian,
>    A silly question ... The next patch that I send which possibly
> handles Arndale and Odroid-XU, should that be based on master or
> staging?

staging please, plus this patch I think.

(normally master is fine but in this case there are relevant changes in
the the master..staging range).



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