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>

diff --git a/Documentation/devicetree/bindings/dma/snps-dma.txt b/Documentation/devicetree/bindings/dma/snps-dma.txt
index db757df7057df69f6f95d4c54f3bc141affd78ed..0bedceed1963548a938db67e7a1ce66b85f63cac 100644 (file)
--- 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 dc053e62f8945b83665263a2a27a8db5f33d299a..e255039866803eeeb0d4282a26c52b8561fc9ba8 100644 (file)
--- 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 313ba10c6224d6cff361806ec0be9bee88ac2c29..570498faadc3dbe926087988b13fea950f5301c0 100644 (file)
--- 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 31ff8113c3defc6fa231662cf0da5b6e795606d4..6dd8cd1820c16b52d23ba9c360a7e7d71bf5d375 100644 (file)
--- 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 98dbc796353fb663ba81fee043cbfce7b6157d5f..53ca9ba6ab4b1bd5721fe49f0998658e6dcf1db4 100644 (file)
--- 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 1a1d58ebffbf1f43179b87d7eafc0071b7af38a3..d443025c5c723fa4304f456433100bd589a9f048 100644 (file)
--- 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 */