Re: [PATCH v3 2/2] DW DMAC: add multi-block property to device tree

[Vinod Koul]

On Fri, Nov 18, 2016 at 09:33:13PM +0200, Andy Shevchenko wrote:
> > @@ -1569,7 +1569,7 @@ int dw_dma_probe(struct dw_dma_chip *chip)
> >     (dwc_params >> DWC_PARAMS_MBLK_EN &
> > 0x1) == 0;
> >     } else {
> >     dwc->block_size = pdata->block_size;
> > -   dwc->nollp = pdata->is_nollp;
> > +   dwc->nollp = pdata->multi_block[i];
> 
> You missed the point. You assign positive value to negative variable.
> It's a bug. Have you tested this? How?
> 
> In case of positive property you have to update DTS. By the way, I'm
> pretty sure that spare13xx boards has auto configuration enabled, though
> it has to be checked with vendor (I assume you may have fast response
> from them).

Yeah why are we not using auto configuration here would be the first
question..

-- 
~Vinod

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Re: [PATCH v3 2/2] DW DMAC: add multi-block property to device tree

[Arnd Bergmann]

On Friday, November 18, 2016 10:12:36 PM CET Eugeniy Paltsev wrote:
> +- multi-block: Multi block transfers supported by hardware per AHB master.
> +  0 (default): not supported, 1: supported.

Please clarify that this is an array with one cell per master.
My first thought was "why is this not a boolean property", and
I'm sure others might misread it the same way.

Arnd

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Re: [PATCH v3 2/2] DW DMAC: add multi-block property to device tree

[Andy Shevchenko]

On Fri, 2016-11-18 at 22:12 +0300, Eugeniy Paltsev wrote:
> Several versions of DW DMAC have multi block transfers hardware
> support. Hardware support of multi block transfers is disabled
> by default if we use DT to configure DMAC and software emulation
> of multi block transfers used instead.
> Add multi-block property, so it is possible to enable hardware
> multi block transfers (if present) via DT.
> 
> Switch from per device is_nollp variable to multi_block array
> to be able enable/disable multi block transfers separately per
> channel.
> 

> Update DT documentation.
> 
> Update existing platform data.

Kinda useless for commit message, but might go after --- delimiter.

> 
> Signed-off-by: Eugeniy Paltsev 
> ---
>  Documentation/devicetree/bindings/dma/snps-dma.txt | 2 ++
>  drivers/dma/dw/core.c  | 2 +-
>  drivers/dma/dw/platform.c  | 5 +
>  drivers/tty/serial/8250/8250_lpss.c| 2 +-
>  include/linux/platform_data/dma-dw.h   | 4 ++--
>  5 files changed, 11 insertions(+), 4 deletions(-)

> --- a/Documentation/devicetree/bindings/dma/snps-dma.txt
> +++ b/Documentation/devicetree/bindings/dma/snps-dma.txt
> @@ -27,6 +27,8 @@ Optional properties:
>    that services interrupts for this device
>  - 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 per AHB
> master.
> +  0 (default): not supported, 1: supported.
>  
>  Example:
>  
> diff --git a/drivers/dma/dw/core.c b/drivers/dma/dw/core.c
> index c2c0a61..f2a3d06 100644
> --- a/drivers/dma/dw/core.c
> +++ b/drivers/dma/dw/core.c
> @@ -1569,7 +1569,7 @@ int dw_dma_probe(struct dw_dma_chip *chip)
>   (dwc_params >> DWC_PARAMS_MBLK_EN &
> 0x1) == 0;
>   } else {
>   dwc->block_size = pdata->block_size;
> - dwc->nollp = pdata->is_nollp;
> + dwc->nollp = pdata->multi_block[i];

You missed the point. You assign positive value to negative variable.
It's a bug. Have you tested this? How?

In case of positive property you have to update DTS. By the way, I'm
pretty sure that spare13xx boards has auto configuration enabled, though
it has to be checked with vendor (I assume you may have fast response
from them).

>   }
>   }
>  

-- 
Andy Shevchenko 
Intel Finland Oy

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[PATCH v3 2/2] DW DMAC: add multi-block property to device tree

[Eugeniy Paltsev]

Several versions of DW DMAC have multi block transfers hardware
support. Hardware support of multi block transfers is disabled
by default if we use DT to configure DMAC and software emulation
of multi block transfers used instead.
Add multi-block property, so it is possible to enable hardware
multi block transfers (if present) via DT.

Switch from per device is_nollp variable to multi_block array
to be able enable/disable multi block transfers separately per
channel.

Update DT documentation.

Update existing platform data.

Signed-off-by: Eugeniy Paltsev 
---
 Documentation/devicetree/bindings/dma/snps-dma.txt | 2 ++
 drivers/dma/dw/core.c  | 2 +-
 drivers/dma/dw/platform.c  | 5 +
 drivers/tty/serial/8250/8250_lpss.c| 2 +-
 include/linux/platform_data/dma-dw.h   | 4 ++--
 5 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/Documentation/devicetree/bindings/dma/snps-dma.txt 
b/Documentation/devicetree/bindings/dma/snps-dma.txt
index 0f55832..03d6d6d 100644
--- a/Documentation/devicetree/bindings/dma/snps-dma.txt
+++ b/Documentation/devicetree/bindings/dma/snps-dma.txt
@@ -27,6 +27,8 @@ Optional properties:
   that services interrupts for this device
 - 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 per AHB master.
+  0 (default): not supported, 1: supported.
 
 Example:
 
diff --git a/drivers/dma/dw/core.c b/drivers/dma/dw/core.c
index c2c0a61..f2a3d06 100644
--- a/drivers/dma/dw/core.c
+++ b/drivers/dma/dw/core.c
@@ -1569,7 +1569,7 @@ int dw_dma_probe(struct dw_dma_chip *chip)
(dwc_params >> DWC_PARAMS_MBLK_EN & 0x1) == 0;
} else {
dwc->block_size = pdata->block_size;
-   dwc->nollp = pdata->is_nollp;
+   dwc->nollp = pdata->multi_block[i];
}
}
 
diff --git a/drivers/dma/dw/platform.c b/drivers/dma/dw/platform.c
index aa7a5c1..b262fd3 100644
--- a/drivers/dma/dw/platform.c
+++ b/drivers/dma/dw/platform.c
@@ -152,6 +152,11 @@ dw_dma_parse_dt(struct platform_device *pdev)
pdata->data_width[tmp] = BIT(arr[tmp] & 0x07);
}
 
+   if (!of_property_read_u32_array(np, "multi-block", arr, nr_masters)) {
+   for (tmp = 0; tmp < nr_masters; tmp++)
+   pdata->multi_block[tmp] = arr[tmp];
+   }
+
return pdata;
 }
 #else
diff --git a/drivers/tty/serial/8250/8250_lpss.c 
b/drivers/tty/serial/8250/8250_lpss.c
index f607946..58cbb30 100644
--- a/drivers/tty/serial/8250/8250_lpss.c
+++ b/drivers/tty/serial/8250/8250_lpss.c
@@ -157,12 +157,12 @@ static int byt_serial_setup(struct lpss8250 *lpss, struct 
uart_port *port)
 static const struct dw_dma_platform_data qrk_serial_dma_pdata = {
.nr_channels = 2,
.is_private = true,
-   .is_nollp = true,
.chan_allocation_order = CHAN_ALLOCATION_ASCENDING,
.chan_priority = CHAN_PRIORITY_ASCENDING,
.block_size = 4095,
.nr_masters = 1,
.data_width = {4},
+   .multi_block = {0},
 };
 
 static void qrk_serial_setup_dma(struct lpss8250 *lpss, struct uart_port *port)
diff --git a/include/linux/platform_data/dma-dw.h 
b/include/linux/platform_data/dma-dw.h
index 5f0e11e..0773bb4 100644
--- a/include/linux/platform_data/dma-dw.h
+++ b/include/linux/platform_data/dma-dw.h
@@ -40,19 +40,18 @@ struct dw_dma_slave {
  * @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_nollp: The device channels does not support multi block transfers.
  * @chan_allocation_order: Allocate channels starting from 0 or 7
  * @chan_priority: Set channel priority increasing from 0 to 7 or 7 to 0.
  * @block_size: Maximum block size supported by the controller
  * @nr_masters: Number of AHB masters supported by the controller
  * @data_width: Maximum data width supported by hardware per AHB master
  * (in bytes, power of 2)
+ * @multi_block: Multi block transfers supported by hardware per AHB master.
  */
 struct dw_dma_platform_data {
unsigned intnr_channels;
boolis_private;
boolis_memcpy;
-   boolis_nollp;
 #define CHAN_ALLOCATION_ASCENDING  0   /* zero to seven */
 #define CHAN_ALLOCATION_DESCENDING 1   /* seven to zero */
unsigned char   chan_allocation_order;
@@ -62,6 +61,7 @@ struct dw_dma_platform_data {
unsigned intblock_size;
unsigned char   nr_masters;
unsigned char   data_width[DW_DMA_MAX_NR_MASTERS];
+   unsigned char   multi_block[DW_DMA_MAX_NR_MASTERS];
 };