On 01/22/2016 03:00 PM, Simon Glass wrote:
Hi Stephen,
On 22 January 2016 at 14:58, Stephen Warren <swar...@wwwdotorg.org> wrote:
On 01/22/2016 02:50 PM, Simon Glass wrote:
Hi Stephen,
On 22 January 2016 at 14:48, Stephen Warren <swar...@wwwdotorg.org> wrote:
On 01/22/2016 01:32 PM, Simon Glass wrote:
Hi Stephen,
On 22 January 2016 at 12:38, Stephen Warren <swar...@wwwdotorg.org>
wrote:
On 01/21/2016 09:03 PM, Simon Glass wrote:
Hi Bin,
On 21 January 2016 at 20:53, Bin Meng <bmeng...@gmail.com> wrote:
On Fri, Jan 22, 2016 at 11:36 AM, Simon Glass <s...@chromium.org>
wrote:
Hi,
On 21 January 2016 at 18:39, Bin Meng <bmeng...@gmail.com> wrote:
Hi Stephen,
On Fri, Jan 22, 2016 at 7:35 AM, Stephen Warren
<swar...@wwwdotorg.org> wrote:
From: Stephen Warren <swar...@nvidia.com>
PCI controllers should be enumerated at startup so that PCI
devices
such as Ethernet controllers are available at startup. Fix
board_init_r()
not to skip calling pci_init() when CONFIG_DM_PCI is defined, and
provide
an implementation of pci_init() for the DM case.
What exact issue are you trying to fix? I posted the same question
on
Simon's patch [1] before. Does your patch and Simon's fix the same
issue?
Note I submitted a similar patch [2] last year for x86 only, to
explicitly trigger the PCI enueration. But it was not accepted.
Fixes: 96350f729c42 ("dm: tegra: net: Convert tegra boards to
driver
model
for Ethernet")
Signed-off-by: Stephen Warren <swar...@nvidia.com>
---
I'm not sure if relying on the side-effects of calling
uclass_{first,ext}_device is the correct approach; is there a more
explicit
way to probe all PCI controllers?
Arguably, perhaps we should introduce a "pci start" command
instead
of
this change to be consistent with e.g. USB. However, that would be
a
regression relative to earlier versions of U-Boot.
---
[1] http://patchwork.ozlabs.org/patch/569323/
[2] http://patchwork.ozlabs.org/patch/500246/
Regards,
Bin
This does go against the driver-model philosophy of lazy init. I
wonder if we should add this patch with a Kconfig option to enable
it?
Then it can be enabled only for boards that need it.
I suspect the issue is somewhere else. On Intel Galileo with a PCI
ethernet, it works fine without such explicit pci init. Which PCI
ethernet driver does not work on Tegra?
It could be because that board probes PCI to get its serial to work.
This could be fixed on Tegra by adding an Ethernet node to the device
tree to cause it to be probed. But I don't think that should be a
requirement.
Since PCI devices are automatically probed via standard bus protocols,
I
believe we shouldn't have to add them to the DT.
However, I could accept that we should add the PCI controller to DT in
order for the controller to be probed, and when that happens, the bus
should
be enumerated thus causing all the Ethernet devices to be probed.
However,
the PCI controller is already in DT, and this process isn't being
kicked
off, so if that's the way it's supposed to work, there's a bug there.
So what do you think about a Kconfig option that tells U-Boot that PCI
must be probed after relocation?
I'm puzzled why anyone would turn off that option.
If PCI is to be used at all, it needs to be probed. The only way I'm
aware
of that it can be probed today is by accidental side-effect of some board
forcibly probing some device that happens to be on a PCI bus (i.e. Bin's
case). In other case, PCI doesn't get automatically probed at boot, and I
don't see any command that allows it to be probed manually. Don't we need
this patch (or your patch linked above) in order to make PCI usable at
all?
If so, why would anyone turn this off?
We try to probe devices only when used. E.g. on beaver, if you are not
net-booting, you actually don't need PCI.
Are you saying that the first network command I execute in U-Boot should
probe Ethernet device and hence PCI devices right now in the current U-Boot
code?
That doesn't work right now. If it did work, that would probably be OK.
Two options:
- Add a 'pci start' command to your script
- Enable the PCI auto-probe Kconfig option
Boards can then choose which they prefer.
I see there's already a "pci enum" command that can be enabled:
#ifdef CONFIG_SYS_LONGHELP
static char pci_help_text[] =
"[bus] [long]\n"
" - short or long list of PCI devices on bus 'bus'\n"
#ifdef CONFIG_CMD_PCI_ENUM
"pci enum\n"
" - re-enumerate PCI buses\n"
#endif
I'm tempted to re-enable that for DM, by making the implementation of
pci_init() exist even with CONFIG_DM_PCI, then enhance
config_distro_bootcmd.h to have it run "pci enum" any time before it
might touch a PCI device, similar to the existing USB and SCSI
enumeration support.
The only wart is that the command help text currently says
"*re-*enumerate PCI buses" rather than just "enumerate PCI buses", which
implies the semantics would always cause an enumeration even on the
second/... execution, whereas it'd be simpler to have it work like "usb
start", i.e. perform enumeration the first time but be a no-op any
second/... time. Am I reading too much into the help text? If not,
should I just rename the command to "pci start" for the DM case? I'm not
sure if PCI hotplug is something we'll need to deal with; that'd be the
only time the different semantics were particular useful.
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