diff mbox

[v3,4/5] dmaengine: xilinx_dma: autodetect whether the HW supports scatter-gather

Message ID 20180625092724.22164-4-andrea.merello@gmail.com (mailing list archive)
State Changes Requested
Headers show

Commit Message

Andrea Merello June 25, 2018, 9:27 a.m. UTC
The AXIDMA and CDMA HW can be either direct-access or scatter-gather
version. These are SW incompatible.

The driver can handle both version: a DT property was used to
tell the driver whether to assume the HW is is scatter-gather mode.

This patch makes the driver to autodetect this information. The DT
property is not required anymore.

No changes for VDMA.

Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: devicetree@vger.kernel.org
Cc: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
Reviewed-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
---
Changes in v2:
	- autodetect only in !VDMA case
Changes in v3:
	- cc DT maintainers/ML
---
 drivers/dma/xilinx/xilinx_dma.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

Comments

Vinod Koul June 29, 2018, 7:37 a.m. UTC | #1
On 25-06-18, 11:27, Andrea Merello wrote:
> The AXIDMA and CDMA HW can be either direct-access or scatter-gather
> version. These are SW incompatible.
> 
> The driver can handle both version: a DT property was used to
                                ^^^^
versions

> tell the driver whether to assume the HW is is scatter-gather mode.
                                           ^^^^^
is in?

> 
> This patch makes the driver to autodetect this information. The DT
> property is not required anymore.
> 
> No changes for VDMA.
> 
> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: devicetree@vger.kernel.org
> Cc: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
> Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
> Reviewed-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
> ---
> Changes in v2:
> 	- autodetect only in !VDMA case
> Changes in v3:
> 	- cc DT maintainers/ML
> ---
>  drivers/dma/xilinx/xilinx_dma.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c
> index 7f0ab904b749..43fcc71ff287 100644
> --- a/drivers/dma/xilinx/xilinx_dma.c
> +++ b/drivers/dma/xilinx/xilinx_dma.c
> @@ -86,6 +86,7 @@
>  #define XILINX_DMA_DMASR_DMA_DEC_ERR		BIT(6)
>  #define XILINX_DMA_DMASR_DMA_SLAVE_ERR		BIT(5)
>  #define XILINX_DMA_DMASR_DMA_INT_ERR		BIT(4)
> +#define XILINX_DMA_DMASR_SG_MASK		BIT(3)
>  #define XILINX_DMA_DMASR_IDLE			BIT(1)
>  #define XILINX_DMA_DMASR_HALTED		BIT(0)
>  #define XILINX_DMA_DMASR_DELAY_MASK		GENMASK(31, 24)
> @@ -406,7 +407,6 @@ struct xilinx_dma_config {
>   * @dev: Device Structure
>   * @common: DMA device structure
>   * @chan: Driver specific DMA channel
> - * @has_sg: Specifies whether Scatter-Gather is present or not
>   * @mcdma: Specifies whether Multi-Channel is present or not
>   * @flush_on_fsync: Flush on frame sync
>   * @ext_addr: Indicates 64 bit addressing is supported by dma device
> @@ -426,7 +426,6 @@ struct xilinx_dma_device {
>  	struct device *dev;
>  	struct dma_device common;
>  	struct xilinx_dma_chan *chan[XILINX_DMA_MAX_CHANS_PER_DEVICE];
> -	bool has_sg;
>  	bool mcdma;
>  	u32 flush_on_fsync;
>  	bool ext_addr;
> @@ -2393,7 +2392,6 @@ static int xilinx_dma_chan_probe(struct xilinx_dma_device *xdev,
>  
>  	chan->dev = xdev->dev;
>  	chan->xdev = xdev;
> -	chan->has_sg = xdev->has_sg;
>  	chan->desc_pendingcount = 0x0;
>  	chan->ext_addr = xdev->ext_addr;
>  	/* This variable ensures that descriptors are not
> @@ -2486,6 +2484,15 @@ static int xilinx_dma_chan_probe(struct xilinx_dma_device *xdev,
>  		chan->stop_transfer = xilinx_dma_stop_transfer;
>  	}
>  
> +	/* check if SG is enabled (only for AXIDMA and CDMA) */
> +	if (xdev->dma_config->dmatype != XDMA_TYPE_VDMA) {
> +		if (dma_ctrl_read(chan, XILINX_DMA_REG_DMASR) &
> +		    XILINX_DMA_DMASR_SG_MASK)

why not read this for VDMA too, will it return false?

> +			chan->has_sg = true;
> +		dev_dbg(chan->dev, "ch %d: SG %s\n", chan->id,
> +			chan->has_sg ? "enabled" : "disabled");

this debug print can be removed
Andrea Merello June 29, 2018, 7:53 a.m. UTC | #2
On Fri, Jun 29, 2018 at 9:37 AM, Vinod <vkoul@kernel.org> wrote:
> On 25-06-18, 11:27, Andrea Merello wrote:
>> The AXIDMA and CDMA HW can be either direct-access or scatter-gather
>> version. These are SW incompatible.
>>
>> The driver can handle both version: a DT property was used to
>                                 ^^^^
> versions
>

OK

>> tell the driver whether to assume the HW is is scatter-gather mode.
>                                            ^^^^^
> is in?

Yes, it is. Thanks

>>
>> This patch makes the driver to autodetect this information. The DT
>> property is not required anymore.
>>
>> No changes for VDMA.
>>
>> Cc: Rob Herring <robh+dt@kernel.org>
>> Cc: Mark Rutland <mark.rutland@arm.com>
>> Cc: devicetree@vger.kernel.org
>> Cc: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
>> Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
>> Reviewed-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
>> ---
>> Changes in v2:
>>       - autodetect only in !VDMA case
>> Changes in v3:
>>       - cc DT maintainers/ML
>> ---
>>  drivers/dma/xilinx/xilinx_dma.c | 14 ++++++++++----
>>  1 file changed, 10 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c
>> index 7f0ab904b749..43fcc71ff287 100644
>> --- a/drivers/dma/xilinx/xilinx_dma.c
>> +++ b/drivers/dma/xilinx/xilinx_dma.c
>> @@ -86,6 +86,7 @@
>>  #define XILINX_DMA_DMASR_DMA_DEC_ERR         BIT(6)
>>  #define XILINX_DMA_DMASR_DMA_SLAVE_ERR               BIT(5)
>>  #define XILINX_DMA_DMASR_DMA_INT_ERR         BIT(4)
>> +#define XILINX_DMA_DMASR_SG_MASK             BIT(3)
>>  #define XILINX_DMA_DMASR_IDLE                        BIT(1)
>>  #define XILINX_DMA_DMASR_HALTED              BIT(0)
>>  #define XILINX_DMA_DMASR_DELAY_MASK          GENMASK(31, 24)
>> @@ -406,7 +407,6 @@ struct xilinx_dma_config {
>>   * @dev: Device Structure
>>   * @common: DMA device structure
>>   * @chan: Driver specific DMA channel
>> - * @has_sg: Specifies whether Scatter-Gather is present or not
>>   * @mcdma: Specifies whether Multi-Channel is present or not
>>   * @flush_on_fsync: Flush on frame sync
>>   * @ext_addr: Indicates 64 bit addressing is supported by dma device
>> @@ -426,7 +426,6 @@ struct xilinx_dma_device {
>>       struct device *dev;
>>       struct dma_device common;
>>       struct xilinx_dma_chan *chan[XILINX_DMA_MAX_CHANS_PER_DEVICE];
>> -     bool has_sg;
>>       bool mcdma;
>>       u32 flush_on_fsync;
>>       bool ext_addr;
>> @@ -2393,7 +2392,6 @@ static int xilinx_dma_chan_probe(struct xilinx_dma_device *xdev,
>>
>>       chan->dev = xdev->dev;
>>       chan->xdev = xdev;
>> -     chan->has_sg = xdev->has_sg;
>>       chan->desc_pendingcount = 0x0;
>>       chan->ext_addr = xdev->ext_addr;
>>       /* This variable ensures that descriptors are not
>> @@ -2486,6 +2484,15 @@ static int xilinx_dma_chan_probe(struct xilinx_dma_device *xdev,
>>               chan->stop_transfer = xilinx_dma_stop_transfer;
>>       }
>>
>> +     /* check if SG is enabled (only for AXIDMA and CDMA) */
>> +     if (xdev->dma_config->dmatype != XDMA_TYPE_VDMA) {
>> +             if (dma_ctrl_read(chan, XILINX_DMA_REG_DMASR) &
>> +                 XILINX_DMA_DMASR_SG_MASK)
>
> why not read this for VDMA too, will it return false?

AFAIK this bit is reserved in VDMA, so reading it can lead to any
random thing.. I would say that potentially it could even be used for
other purposes in future IP releases..

>> +                     chan->has_sg = true;
>> +             dev_dbg(chan->dev, "ch %d: SG %s\n", chan->id,
>> +                     chan->has_sg ? "enabled" : "disabled");
>
> this debug print can be removed

IMHO if someone will ever enable debug prints for debugging something
and then he/she reports us a log, then it would be useful to see in
the log if the IP was SG or not..

> --
> ~Vinod
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diff mbox

Patch

diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c
index 7f0ab904b749..43fcc71ff287 100644
--- a/drivers/dma/xilinx/xilinx_dma.c
+++ b/drivers/dma/xilinx/xilinx_dma.c
@@ -86,6 +86,7 @@ 
 #define XILINX_DMA_DMASR_DMA_DEC_ERR		BIT(6)
 #define XILINX_DMA_DMASR_DMA_SLAVE_ERR		BIT(5)
 #define XILINX_DMA_DMASR_DMA_INT_ERR		BIT(4)
+#define XILINX_DMA_DMASR_SG_MASK		BIT(3)
 #define XILINX_DMA_DMASR_IDLE			BIT(1)
 #define XILINX_DMA_DMASR_HALTED		BIT(0)
 #define XILINX_DMA_DMASR_DELAY_MASK		GENMASK(31, 24)
@@ -406,7 +407,6 @@  struct xilinx_dma_config {
  * @dev: Device Structure
  * @common: DMA device structure
  * @chan: Driver specific DMA channel
- * @has_sg: Specifies whether Scatter-Gather is present or not
  * @mcdma: Specifies whether Multi-Channel is present or not
  * @flush_on_fsync: Flush on frame sync
  * @ext_addr: Indicates 64 bit addressing is supported by dma device
@@ -426,7 +426,6 @@  struct xilinx_dma_device {
 	struct device *dev;
 	struct dma_device common;
 	struct xilinx_dma_chan *chan[XILINX_DMA_MAX_CHANS_PER_DEVICE];
-	bool has_sg;
 	bool mcdma;
 	u32 flush_on_fsync;
 	bool ext_addr;
@@ -2393,7 +2392,6 @@  static int xilinx_dma_chan_probe(struct xilinx_dma_device *xdev,
 
 	chan->dev = xdev->dev;
 	chan->xdev = xdev;
-	chan->has_sg = xdev->has_sg;
 	chan->desc_pendingcount = 0x0;
 	chan->ext_addr = xdev->ext_addr;
 	/* This variable ensures that descriptors are not
@@ -2486,6 +2484,15 @@  static int xilinx_dma_chan_probe(struct xilinx_dma_device *xdev,
 		chan->stop_transfer = xilinx_dma_stop_transfer;
 	}
 
+	/* check if SG is enabled (only for AXIDMA and CDMA) */
+	if (xdev->dma_config->dmatype != XDMA_TYPE_VDMA) {
+		if (dma_ctrl_read(chan, XILINX_DMA_REG_DMASR) &
+		    XILINX_DMA_DMASR_SG_MASK)
+			chan->has_sg = true;
+		dev_dbg(chan->dev, "ch %d: SG %s\n", chan->id,
+			chan->has_sg ? "enabled" : "disabled");
+	}
+
 	/* Initialize the tasklet */
 	tasklet_init(&chan->tasklet, xilinx_dma_do_tasklet,
 			(unsigned long)chan);
@@ -2624,7 +2631,6 @@  static int xilinx_dma_probe(struct platform_device *pdev)
 		return PTR_ERR(xdev->regs);
 
 	/* Retrieve the DMA engine properties from the device tree */
-	xdev->has_sg = of_property_read_bool(node, "xlnx,include-sg");
 	xdev->max_buffer_len = GENMASK(XILINX_DMA_MAX_TRANS_LEN_MAX - 1, 0);
 
 	if (xdev->dma_config->dmatype == XDMA_TYPE_AXIDMA) {