patch "driver core: platform: Initialize dma_parms for platform devices" added to char-misc-next

This is a note to let you know that I've just added the patch titled

driver core: platform: Initialize dma_parms for platform devices

to my char-misc git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
in the char-misc-next branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will also be merged in the next major kernel release during the merge window.

If you have any questions about this process, please let me know.

From 7c8978c0837d40c302f5e90d24c298d9ca9fc097 Mon Sep 17 00:00:00 2001
From: Ulf Hansson <[email protected]>
Date: Wed, 25 Mar 2020 12:34:06 +0100
Subject: driver core: platform: Initialize dma_parms for platform devices

It's currently the platform driver's responsibility to initialize the pointer, dma_parms, for its corresponding struct device. The benefit with this approach allows us to avoid the initialization and to not waste memory for the struct device_dma_parameters, as this can be decided on a case by case basis.

However, it has turned out that this approach is not very practical. Not only does it lead to open coding, but also to real errors. In principle callers of dma_set_max_seg_size() doesn't check the error code, but just assumes it succeeds.

For these reasons, let's do the initialization from the common platform bus at the device registration point. This also follows the way the PCI devices are being managed, see pci_device_add().

---
 drivers/base/platform.c         | 1 +
 include/linux/platform_device.h | 1 +
 2 files changed, 2 insertions(+)

index b5ce7b085795..46abbfb52655 100644
@@ -512,6 +512,7 @@ int platform_device_add(struct platform_device *pdev)
 		pdev->dev.parent = &platform_bus;
 
 	pdev->dev.bus = &platform_bus_type;
+	pdev->dev.dma_parms = &pdev->dma_parms;
 
 	switch (pdev->id) {
 	default:

index 041bfa412aa0..81900b3cbe37 100644
@@ -25,6 +25,7 @@ struct platform_device {
 	bool		id_auto;
 	struct device	dev;
 	u64		platform_dma_mask;
+	struct device_dma_parameters dma_parms;
 	u32		num_resources;
 	struct resource	*resource;
 

2.26.0