Hi Thomas,

Sorry I totally missed this patch.

On Wed, Dec 8, 2021 at 5:04 AM Thomas Bogendoerfer
[off-list ref] wrote:

On Wed, Nov 17, 2021 at 05:03:15PM +0800, Tiezhu Yang wrote:

quoted

After commit 9f76779f2418 ("MIPS: implement architecture-specific
'pci_remap_iospace()'"), there exists the following warning on the
Loongson64 platform:

    loongson-pci 1a000000.pci:       IO 0x0018020000..0x001803ffff -> 0x0000020000
    loongson-pci 1a000000.pci:      MEM 0x0040000000..0x007fffffff -> 0x0040000000
    ------------[ cut here ]------------
    WARNING: CPU: 2 PID: 1 at arch/mips/pci/pci-generic.c:55 pci_remap_iospace+0x84/0x90
    resource start address is not zero
    ...
    Call Trace:
    [<ffffffff8020dc78>] show_stack+0x40/0x120
    [<ffffffff80cf4a0c>] dump_stack_lvl+0x58/0x74
    [<ffffffff8023a0b0>] __warn+0xe0/0x110
    [<ffffffff80cee02c>] warn_slowpath_fmt+0xa4/0xd0
    [<ffffffff80cecf24>] pci_remap_iospace+0x84/0x90
    [<ffffffff807f9864>] devm_pci_remap_iospace+0x5c/0xb8
    [<ffffffff808121b0>] devm_of_pci_bridge_init+0x178/0x1f8
    [<ffffffff807f4000>] devm_pci_alloc_host_bridge+0x78/0x98
    [<ffffffff80819454>] loongson_pci_probe+0x34/0x160
    [<ffffffff809203cc>] platform_probe+0x6c/0xe0
    [<ffffffff8091d5d4>] really_probe+0xbc/0x340
    [<ffffffff8091d8f0>] __driver_probe_device+0x98/0x110
    [<ffffffff8091d9b8>] driver_probe_device+0x50/0x118
    [<ffffffff8091dea0>] __driver_attach+0x80/0x118
    [<ffffffff8091b280>] bus_for_each_dev+0x80/0xc8
    [<ffffffff8091c6d8>] bus_add_driver+0x130/0x210
    [<ffffffff8091ead4>] driver_register+0x8c/0x150
    [<ffffffff80200a8c>] do_one_initcall+0x54/0x288
    [<ffffffff811a5320>] kernel_init_freeable+0x27c/0x2e4
    [<ffffffff80cfc380>] kernel_init+0x2c/0x134
    [<ffffffff80205a2c>] ret_from_kernel_thread+0x14/0x1c
    ---[ end trace e4a0efe10aa5cce6 ]---
    loongson-pci 1a000000.pci: error -19: failed to map resource [io  0x20000-0x3ffff]

We can see that the resource start address is 0x0000020000, because
the ISA Bridge used the zero address which is defined in the dts file
arch/mips/boot/dts/loongson/ls7a-pch.dtsi:

    ISA Bridge: /bus@10000000/isa@18000000
    IO 0x0000000018000000..0x000000001801ffff  ->  0x0000000000000000

The architecture-independent function pci_remap_iospace() works well
for Loongson64, so just do not define architecture-specific function
pci_remap_iospace() under MACH_LOONGSON64.

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
 arch/mips/include/asm/pci.h | 2 ++
 arch/mips/pci/pci-generic.c | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/arch/mips/include/asm/pci.h b/arch/mips/include/asm/pci.h
index 421231f..5d647cb 100644
--- a/arch/mips/include/asm/pci.h
+++ b/arch/mips/include/asm/pci.h

@@ -21,8 +21,10 @@
 #include <linux/of.h>

 #ifdef CONFIG_PCI_DRIVERS_GENERIC
+#ifndef CONFIG_MACH_LOONGSON64
 #define pci_remap_iospace pci_remap_iospace
 #endif
+#endif

I am not sure but maybe just remove the WARN_ON and the if from the
implementation allow also this platform to work with specific MIPS
helper? The only problem I initially see is that the loongson64 puts
isa bridge resource in 0x0 and thus the warning appears. I have to
mention because I don't know other MIPS based SoCs with PCI but
'pci_remap_iospace()' should properly fit all of them... Is a kind of
generic implementation using MIPS 'set_io_port_base()' and 'ioremap()'
for properly remapping things...

I agree this is cleaner than the CONFIG_MACH_LOONGSON64 ifdef stuff. I
have tested this changes in mt7621 ralink platform and all seem to
work, so in case you want to include this, feel free to add my:

Tested-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Acked-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>

Thomas, if you prefer me to send this as a more formal PATCH, please
let me know.

Best regards,
    Sergio Paracuellos

Thomas.

--
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]