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[PATCH wireless-drivers-next] bcma: get SoC device struct & copy its DMA

To: Kalle Valo <>,
Subject: [PATCH wireless-drivers-next] bcma: get SoC device struct & copy its DMA params to the subdevices
From: Rafał Miłecki <>
Date: Mon, 21 Jan 2019 11:11:21 +0100
Cc: Hauke Mehrtens <>, Rafał Miłecki <>,, Christoph Hellwig <>, Linus Walleij <>
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From: Rafał Miłecki <>

For bus devices to be fully usable it's required to set their DMA

For years it has been missing and remained unnoticed because of
mips_dma_alloc_coherent() silently handling the empty coherent_dma_mask.
Kernel 4.19 came with a lot of DMA changes and caused a regression on
the bcm47xx. Starting with the commit f8c55dc6e828 ("MIPS: use generic
dma noncoherent ops for simple noncoherent platforms") DMA coherent
allocations just fail. Example:
[    1.114914] bgmac_bcma bcma0:2: Allocation of TX ring 0x200 failed
[    1.121215] bgmac_bcma bcma0:2: Unable to alloc memory for DMA
[    1.127626] bgmac_bcma: probe of bcma0:2 failed with error -12
[    1.133838] bgmac_bcma: Broadcom 47xx GBit MAC driver loaded

This change fixes above regression in addition to the MIPS bcm47xx
commit 321c46b91550 ("MIPS: BCM47XX: Setup struct device for the SoC").

It also fixes another *old* GPIO regression caused by a parent pointing
to the NULL:
[    0.157054] missing gpiochip .dev parent pointer
[    0.157287] bcma: bus0: Error registering GPIO driver: -22
introduced by the commit 74f4e0cc6108 ("bcma: switch GPIO portions to

Fixes: f8c55dc6e828 ("MIPS: use generic dma noncoherent ops for simple 
noncoherent platforms")
Fixes: 74f4e0cc6108 ("bcma: switch GPIO portions to use GPIOLIB_IRQCHIP")
Cc: Christoph Hellwig <>
Cc: Linus Walleij <>
Signed-off-by: Rafał Miłecki <>
While this patch is a regression fix, it depends on a change present in
the wireless-drivers-next.git:
bcma: keep a direct pointer to the struct device

That's why I suggest pushing it into the wireless-drivers-next.git and I
can take care of picking it for the later.

Another option would be cherry-picking commit 5a1c18b761dd ("bcma: keep
a direct pointer to the struct device") to the wireless-drivers.git but
I don't think it's a common practice.
 drivers/bcma/host_soc.c       | 2 ++
 drivers/bcma/main.c           | 6 +++++-
 include/linux/bcma/bcma_soc.h | 1 +
 3 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/bcma/host_soc.c b/drivers/bcma/host_soc.c
index c8073b509a2b..1fdfb704f22d 100644
--- a/drivers/bcma/host_soc.c
+++ b/drivers/bcma/host_soc.c
@@ -191,6 +191,8 @@ int __init bcma_host_soc_init(struct bcma_soc *soc)
        struct bcma_bus *bus = &soc->bus;
        int err;
+       bus->dev = soc->dev;
        /* Scan bus and initialize it */
        err = bcma_bus_early_register(bus);
        if (err)
diff --git a/drivers/bcma/main.c b/drivers/bcma/main.c
index 6535614a7dc1..433ca5e2ed2c 100644
--- a/drivers/bcma/main.c
+++ b/drivers/bcma/main.c
@@ -236,12 +236,16 @@ EXPORT_SYMBOL(bcma_core_irq);
 void bcma_prepare_core(struct bcma_bus *bus, struct bcma_device *core)
+       struct device *dev = &core->dev;
        core->dev.release = bcma_release_core_dev;
        core->dev.bus = &bcma_bus_type;
        dev_set_name(&core->dev, "bcma%d:%d", bus->num, core->core_index);
        core->dev.parent = bus->dev;
-       if (bus->dev)
+       if (bus->dev) {
                bcma_of_fill_device(bus->dev, core);
+               dma_coerce_mask_and_coherent(dev, bus->dev->coherent_dma_mask);
+       }
        switch (bus->hosttype) {
        case BCMA_HOSTTYPE_PCI:
diff --git a/include/linux/bcma/bcma_soc.h b/include/linux/bcma/bcma_soc.h
index 7cca5f859a90..f3c43519baa7 100644
--- a/include/linux/bcma/bcma_soc.h
+++ b/include/linux/bcma/bcma_soc.h
@@ -6,6 +6,7 @@
 struct bcma_soc {
        struct bcma_bus bus;
+       struct device *dev;
 int __init bcma_host_soc_register(struct bcma_soc *soc);

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