[RFC/PATCH 5/9] of: dma: Split of_configure_dma() into mask and ops configuration

Will Deacon
2015-05-28T13:01:19Z

On Fri, May 15, 2015 at 12:00:06AM +0100, Laurent Pinchart wrote:
> The of_configure_dma() function configures both the DMA masks and ops.
> Moving DMA ops configuration to probe time would thus also delay
> configuration of the DMA masks, which might not be safe. To avoid issues
> split the configuration in two to allow keeping masks configuration at
> device add time and move ops configuration to device probe time.
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> ---
> drivers/of/device.c | 48 ++++++++++++++++++++++++++++++++++-------------
> drivers/of/of_pci.c | 3 ++-
> drivers/of/platform.c | 6 ++++--
> include/linux/of_device.h | 11 +++++++++--
> 4 files changed, 50 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/of/device.c b/drivers/of/device.c
> index f1b84f464fe1..3cb3f78a6d13 100644
> --- a/drivers/of/device.c
> +++ b/drivers/of/device.c
> @@ -70,7 +70,7 @@ int of_device_add(struct platform_device *ofdev)
> }
>
> /**
> - * of_dma_configure - Setup DMA configuration
> + * of_dma_configure - Setup DMA masks and offset
> * @dev: Device to apply DMA configuration
> * @np: Pointer to OF node having DMA configuration
> *
> @@ -81,13 +81,11 @@ int of_device_add(struct platform_device *ofdev)
> * can use a platform bus notifier and handle BUS_NOTIFY_ADD_DEVICE events
> * to fix up DMA configuration.
> */
> -void of_dma_configure(struct device *dev, struct device_node *np)
> +void of_dma_configure_masks(struct device *dev, struct device_node *np)
> {
> - u64 dma_addr, paddr, size;
> - int ret;
> - bool coherent;
> + u64 dma_addr, paddr, size, range_mask;
> unsigned long offset;
> - struct iommu_ops *iommu;
> + int ret;
>
> /*
> * Set default coherent_dma_mask to 32 bit. Drivers are expected to
> @@ -105,9 +103,10 @@ void of_dma_configure(struct device *dev, struct device_node *np)
>
> ret = of_dma_get_range(np, &dma_addr, &paddr, &size);
> if (ret < 0) {
> - dma_addr = offset = 0;
> - size = dev->coherent_dma_mask + 1;
> + range_mask = dev->coherent_dma_mask + 1;

Hmm, do we still want this '+ 1'...

> + offset = 0;
> } else {
> + range_mask = DMA_BIT_MASK(ilog2(dma_addr + size));
> offset = PFN_DOWN(paddr - dma_addr);
> dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", offset);
> }
> @@ -118,10 +117,31 @@ void of_dma_configure(struct device *dev, struct device_node *np)
> * Limit coherent and dma mask based on size and default mask
> * set by the driver.
> */
> - dev->coherent_dma_mask = min(dev->coherent_dma_mask,
> - DMA_BIT_MASK(ilog2(dma_addr + size)));
> - *dev->dma_mask = min((*dev->dma_mask),
> - DMA_BIT_MASK(ilog2(dma_addr + size)));
> + dev->coherent_dma_mask = min(dev->coherent_dma_mask, range_mask);

... if we now compare directly with the mask here? In fact, this setting
of the coherent_dma_mask could just belong in the else clause, no?

> + *dev->dma_mask = min((*dev->dma_mask), range_mask);

Similar comment here, but we need to do this for both cases I guess.

> +}
> +EXPORT_SYMBOL_GPL(of_dma_configure_masks);
> +
> +/**
> + * of_dma_configure_ops - Setup DMA operations
> + * @dev: Device to apply DMA configuration
> + * @np: Pointer to OF node having DMA configuration
> + *
> + * Try to get devices's DMA configuration from DT and update it

Weird spelling.

Will