On 01/10/2017 10:12 AM, Bjorn Helgaas wrote:
> Hi Murali,
>
> On Wed, Jan 04, 2017 at 02:32:30PM -0500, Murali Karicheri wrote:
>> Recent fixes for iATU unroll support introduced a bug that causes
>> asynchronous external abort in Keystone PCIe h/w which doesn't have
>> ATU port and the corresponding register. So the check should be moved
>> below where dw_pcie_prog_outbound_atu() is called to avoid that
>> being called on keystine PCIe h/w.
>>
>> Here is the backtrace
>>
>> [ 0.771174] OF: PCI: MEM 0x60000000..0x6fffffff -> 0x60000000
>> [ 0.778118] Unhandled fault: asynchronous external abort (0x1211) at 0x00000000
>> [ 0.785548] pgd = c0003000
>> [ 0.788347] [00000000] *pgd=80000800004003, *pmd=00000000
>> [ 0.793864] Internal error: : 1211 [#1] PREEMPT SMP ARM
>> [ 0.799197] Modules linked in:
>> [ 0.802351] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.9.0-00009-g6ff59d2-dirty #7
>> [ 0.810130] Hardware name: Keystone
>> [ 0.813717] task: eb878000 task.stack: eb866000
>> [ 0.818356] PC is at dw_pcie_setup_rc+0x24/0x380
>> [ 0.823083] LR is at ks_pcie_host_init+0x10/0x170
>>
>> Fixes: 416379f9ebde ("PCI: designware: Check for iATU unroll support after initializing host")
>
> I tentatively applied this to for-linus for v4.10, with a stable tag
> for v4.9+.
>
Ok Thanks!
> The patch itself mostly makes sense in terms of the code: we only use
> iatu_unroll_enabled in dw_pcie_prog_outbound_atu(). We only call that
> when "!pp->ops->rd_other_conf" or "!pp->ops->wr_other_conf".
>
> So it makes sense that we only need to initialize iatu_unroll_enabled
> in those cases. But the current patch only initializes it if
> "!pp->ops->rd_other_conf".
>
I think the code before also should have checked for both
if ((!pp->ops->rd_other_conf) && (!pp->ops->wr_other_conf))
The assumption was if rd_other_conf is Null, the platform provides
both rd_other_conf and wr_other_conf. I see I have added this API
to support Keystone and the above assumption is true so far.
It make sense to fix it if you agree.
> If we had "pp->ops->rd_other_conf && !pp->ops->wr_other_conf", we
> would use iatu_unroll_enabled uninitialized in the
> dw_pcie_wr_other_conf() path. I suppose that's an invalid
Yes. So we need to fix the above to make the code correct instead
of leaving it exposed.
> configuration, but it'd be better if we didn't have to rely on the
> host drivers to avoid that configuration.
You mean to introduce the check in the designware core code above
right?
Murali
>
> It's not obvious how this is connected to 416379f9ebde, though. It
> *looks* like we call dw_pcie_iatu_unroll_enabled() on Keystone both
> before and after that commit, so it seems like the external abort
> should have happened even before it.
>
You are right. The problem was introduced by
commit a0601a47053714eecec726aea5ebcd829f817497
Author: Joao Pinto <Joao.Pinto@xxxxxxxxxxxx>
Date: Wed Aug 10 11:02:39 2016 +0100
PCI: designware: Add iATU Unroll feature
which is fixed by commit 416379f9ebde and is again fixed by my
commit. So probably I should have added both commits in
my description.
Murali
>> Signed-off-by: Murali Karicheri <m-karicheri2@xxxxxx>
>> Tested-by: Kishon Vijay Abraham I <kishon@xxxxxx>
>> ---
>> - Applies to pci/master
>> - Bug was introduced in v4.9
>> - Tested on K2E EVM with SATA and DRA7-EVM with an intel PCI ethernet card
>>
>> drivers/pci/host/pcie-designware.c | 10 +++++-----
>> 1 file changed, 5 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/pci/host/pcie-designware.c b/drivers/pci/host/pcie-designware.c
>> index bed1999..af8f6e9 100644
>> --- a/drivers/pci/host/pcie-designware.c
>> +++ b/drivers/pci/host/pcie-designware.c
>> @@ -807,11 +807,6 @@ void dw_pcie_setup_rc(struct pcie_port *pp)
>> {
>> u32 val;
>>
>> - /* get iATU unroll support */
>> - pp->iatu_unroll_enabled = dw_pcie_iatu_unroll_enabled(pp);
>> - dev_dbg(pp->dev, "iATU unroll: %s\n",
>> - pp->iatu_unroll_enabled ? "enabled" : "disabled");
>> -
>> /* set the number of lanes */
>> val = dw_pcie_readl_rc(pp, PCIE_PORT_LINK_CONTROL);
>> val &= ~PORT_LINK_MODE_MASK;
>> @@ -882,6 +877,11 @@ void dw_pcie_setup_rc(struct pcie_port *pp)
>> * we should not program the ATU here.
>> */
>> if (!pp->ops->rd_other_conf) {
>> + /* get iATU unroll support */
>> + pp->iatu_unroll_enabled = dw_pcie_iatu_unroll_enabled(pp);
>> + dev_dbg(pp->dev, "iATU unroll: %s\n",
>> + pp->iatu_unroll_enabled ? "enabled" : "disabled");
>> +
>> dw_pcie_prog_outbound_atu(pp, PCIE_ATU_REGION_INDEX0,
>> PCIE_ATU_TYPE_MEM, pp->mem_base,
>> pp->mem_bus_addr, pp->mem_size);
>> --
>> 1.9.1
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-pci" in
>> the body of a message to majordomo@xxxxxxxxxxxxxxx
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
Murali Karicheri
Linux Kernel, Keystone
--
To unsubscribe from this list: send the line "unsubscribe linux-pci" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
