Subject: [PATCH] bcma: get SoC device struct & copy its DMA params to the subdevices
From: Rafał Miłecki <[email-masked]>

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

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
use GPIOLIB_IRQCHIP").

Fixes: f8c55dc6e828 ("MIPS: use generic dma noncoherent ops for simple noncoherent platforms")
Fixes: 74f4e0cc6108 ("bcma: switch GPIO portions to use GPIOLIB_IRQCHIP")
Cc: [email-masked]
Cc: Christoph Hellwig <[email-masked]>
Cc: Linus Walleij <[email-masked]>
Signed-off-by: Rafał Miłecki <[email-masked]>
---

--- a/drivers/bcma/host_soc.c
+++ b/drivers/bcma/host_soc.c
@@ -191,6 +191,8 @@ int __init bcma_host_soc_init(struct bcm
 	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)
--- 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: