From d7dba6be0f31ae61f5f3296aa130f45d57d30f74 Mon Sep 17 00:00:00 2001
From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Date: Mon, 7 Jan 2019 13:07:36 +0200
Subject: [PATCH] dmaengine: dw: Remove misleading is_private property
The commit a9ddb575d6d6
("dmaengine: dw_dmac: Enhance device tree support")
introduces is_private property in uncertain understanding what does it mean.
First of all, documentation defines DMA_PRIVATE capability as
Documentation/crypto/async-tx-api.txt:
The DMA_PRIVATE capability flag is used to tag dma devices that should not be
used by the general-purpose allocator. It can be set at initialization time
if it is known that a channel will always be private. Alternatively,
it is set when dma_request_channel() finds an unused "public" channel.
A couple caveats to note when implementing a driver and consumer:
1/ Once a channel has been privately allocated it will no longer be
considered by the general-purpose allocator even after a call to
dma_release_channel().
2/ Since capabilities are specified at the device level a dma_device with
multiple channels will either have all channels public, or all channels
private.
Documentation/driver-api/dmaengine/provider.rst:
- DMA_PRIVATE
The devices only supports slave transfers, and as such isn't available
for async transfers.
The capability had been introduced by the commit 59b5ec21446b
("dmaengine: introduce dma_request_channel and private channels")
and some code didn't changed from that times ever.
Taking into consideration above and the fact that on all known platforms
Synopsys DesignWare DMA engine is attached to serve slave transfers,
the DMA_PRIVATE capability must be enabled for this device unconditionally.
Otherwise, as rightfully noticed in drivers/dma/at_xdmac.c:
/*
* Without DMA_PRIVATE the driver is not able to allocate more than
* one channel, second allocation fails in private_candidate.
*/
because of of a caveats mentioned in above documentation excerpts.
So, remove conditional around DMA_PRIVATE followed by removal leftovers.
If someone wonders, DMA_PRIVATE can be not used if and only if the all channels
of the DMA controller are supposed to serve memory-to-memory like operations.
For example, EP93xx has two controllers, one of which can only perform
memory-to-memory transfers
Note, this change doesn't affect dmatest to be able to test such controllers.
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> (maintainer:SERIAL DRIVERS)
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
---
Documentation/devicetree/bindings/dma/snps-dma.txt | 2 --
drivers/dma/dw/core.c | 4 +---
drivers/dma/dw/pci.c | 1 -
drivers/dma/dw/platform.c | 3 ---
drivers/tty/serial/8250/8250_lpss.c | 1 -
include/linux/platform_data/dma-dw.h | 3 ---
6 files changed, 1 insertion(+), 13 deletions(-)
diff --git a/Documentation/devicetree/bindings/dma/snps-dma.txt b/Documentation/devicetree/bindings/dma/snps-dma.txt
index db757df7057df..0bedceed19635 100644
--- a/Documentation/devicetree/bindings/dma/snps-dma.txt
+++ b/Documentation/devicetree/bindings/dma/snps-dma.txt
@@ -23,8 +23,6 @@ Deprecated properties:
Optional properties:
-- is_private: The device channels should be marked as private and not for by the
- general purpose DMA channel allocator. False if not passed.
- multi-block: Multi block transfers supported by hardware. Array property with
one cell per channel. 0: not supported, 1 (default): supported.
- snps,dma-protection-control: AHB HPROT[3:1] protection setting.
diff --git a/drivers/dma/dw/core.c b/drivers/dma/dw/core.c
index dc053e62f8945..e255039866803 100644
--- a/drivers/dma/dw/core.c
+++ b/drivers/dma/dw/core.c
@@ -1227,7 +1227,6 @@ int dw_dma_probe(struct dw_dma_chip *chip)
pdata->block_size = dma_readl(dw, MAX_BLK_SIZE);
/* Fill platform data with the default values */
- pdata->is_private = true;
pdata->is_memcpy = true;
pdata->chan_allocation_order = CHAN_ALLOCATION_ASCENDING;
pdata->chan_priority = CHAN_PRIORITY_ASCENDING;
@@ -1340,8 +1339,7 @@ int dw_dma_probe(struct dw_dma_chip *chip)
/* Set capabilities */
dma_cap_set(DMA_SLAVE, dw->dma.cap_mask);
- if (pdata->is_private)
- dma_cap_set(DMA_PRIVATE, dw->dma.cap_mask);
+ dma_cap_set(DMA_PRIVATE, dw->dma.cap_mask);
if (pdata->is_memcpy)
dma_cap_set(DMA_MEMCPY, dw->dma.cap_mask);
diff --git a/drivers/dma/dw/pci.c b/drivers/dma/dw/pci.c
index 313ba10c6224d..570498faadc3d 100644
--- a/drivers/dma/dw/pci.c
+++ b/drivers/dma/dw/pci.c
@@ -17,7 +17,6 @@
static struct dw_dma_platform_data mrfld_pdata = {
.nr_channels = 8,
- .is_private = true,
.is_memcpy = true,
.is_idma32 = true,
.chan_allocation_order = CHAN_ALLOCATION_ASCENDING,
diff --git a/drivers/dma/dw/platform.c b/drivers/dma/dw/platform.c
index 31ff8113c3def..6dd8cd1820c16 100644
--- a/drivers/dma/dw/platform.c
+++ b/drivers/dma/dw/platform.c
@@ -128,9 +128,6 @@ dw_dma_parse_dt(struct platform_device *pdev)
pdata->nr_masters = nr_masters;
pdata->nr_channels = nr_channels;
- if (of_property_read_bool(np, "is_private"))
- pdata->is_private = true;
-
/*
* All known devices, which use DT for configuration, support
* memory-to-memory transfers. So enable it by default.
diff --git a/drivers/tty/serial/8250/8250_lpss.c b/drivers/tty/serial/8250/8250_lpss.c
index 98dbc796353fb..53ca9ba6ab4b1 100644
--- a/drivers/tty/serial/8250/8250_lpss.c
+++ b/drivers/tty/serial/8250/8250_lpss.c
@@ -153,7 +153,6 @@ static int byt_serial_setup(struct lpss8250 *lpss, struct uart_port *port)
#ifdef CONFIG_SERIAL_8250_DMA
static const struct dw_dma_platform_data qrk_serial_dma_pdata = {
.nr_channels = 2,
- .is_private = true,
.chan_allocation_order = CHAN_ALLOCATION_ASCENDING,
.chan_priority = CHAN_PRIORITY_ASCENDING,
.block_size = 4095,
diff --git a/include/linux/platform_data/dma-dw.h b/include/linux/platform_data/dma-dw.h
index 1a1d58ebffbf1..d443025c5c723 100644
--- a/include/linux/platform_data/dma-dw.h
+++ b/include/linux/platform_data/dma-dw.h
@@ -38,8 +38,6 @@ struct dw_dma_slave {
/**
* struct dw_dma_platform_data - Controller configuration parameters
* @nr_channels: Number of channels supported by hardware (max 8)
- * @is_private: The device channels should be marked as private and not for
- * by the general purpose DMA channel allocator.
* @is_memcpy: The device channels do support memory-to-memory transfers.
* @is_idma32: The type of the DMA controller is iDMA32
* @chan_allocation_order: Allocate channels starting from 0 or 7
@@ -53,7 +51,6 @@ struct dw_dma_slave {
*/
struct dw_dma_platform_data {
unsigned int nr_channels;
- bool is_private;
bool is_memcpy;
bool is_idma32;
#define CHAN_ALLOCATION_ASCENDING 0 /* zero to seven */
--
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