[2/2] PCI: rcar: Recalculate inbound range alignment for each controller entry

From: Marek Vasut <marek.vasut+renesas@gmail.com>

Due to hardware constraints, the size of each inbound range entry
populated into the controller cannot be larger than the alignment
of the entry's start address. Currently, the alignment for each
"dma-ranges" inbound range is calculated only once for each range
and the increment for programming the controller is also derived
from it only once. Thus, a "dma-ranges" entry describing a memory
at 0x48000000 and size 0x38000000 would lead to multiple controller
entries, each 0x08000000 long.

This is inefficient, especially considering that by adding the size
to the start address, the alignment increases. This patch moves the
alignment calculation into the loop populating the controller entries,
thus updating the alignment for each controller entry.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Wolfram Sang <wsa@the-dreams.de>
Cc: linux-renesas-soc@vger.kernel.org
To: linux-pci@vger.kernel.org
---
 drivers/pci/controller/pcie-rcar.c | 33 +++++++++++++++---------------
 1 file changed, 17 insertions(+), 16 deletions(-)

On Tue, Jul 09, 2019 at 03:15:59AM +0200, marek.vasut@gmail.com wrote:
> From: Marek Vasut <marek.vasut+renesas@gmail.com>
> 
> Due to hardware constraints, the size of each inbound range entry
> populated into the controller cannot be larger than the alignment
> of the entry's start address. Currently, the alignment for each
> "dma-ranges" inbound range is calculated only once for each range
> and the increment for programming the controller is also derived
> from it only once. Thus, a "dma-ranges" entry describing a memory
> at 0x48000000 and size 0x38000000 would lead to multiple controller
> entries, each 0x08000000 long.
> 
> This is inefficient, especially considering that by adding the size
> to the start address, the alignment increases. This patch moves the
> alignment calculation into the loop populating the controller entries,
> thus updating the alignment for each controller entry.
> 
> Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
> Cc: Geert Uytterhoeven <geert+renesas@glider.be>
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> Cc: Wolfram Sang <wsa@the-dreams.de>
> Cc: linux-renesas-soc@vger.kernel.org
> To: linux-pci@vger.kernel.org

Reviewed-by: Simon Horman <horms+renesas@verge.net.au>

> ---
>  drivers/pci/controller/pcie-rcar.c | 33 +++++++++++++++---------------
>  1 file changed, 17 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/pci/controller/pcie-rcar.c b/drivers/pci/controller/pcie-rcar.c
> index 938adff4148f..48f361b5d690 100644
> --- a/drivers/pci/controller/pcie-rcar.c
> +++ b/drivers/pci/controller/pcie-rcar.c
> @@ -1029,25 +1029,26 @@ static int rcar_pcie_inbound_ranges(struct rcar_pcie *pcie,
>  	if (restype & IORESOURCE_PREFETCH)
>  		flags |= LAM_PREFETCH;
>  
> -	/*
> -	 * If the size of the range is larger than the alignment of the start
> -	 * address, we have to use multiple entries to perform the mapping.
> -	 */
> -	if (cpu_addr > 0) {
> -		unsigned long nr_zeros = __ffs64(cpu_addr);
> -		u64 alignment = 1ULL << nr_zeros;
> +	while (cpu_addr < cpu_end) {
> +		/*
> +		 * If the size of the range is larger than the alignment of
> +		 * the start address, we have to use multiple entries to
> +		 * perform the mapping.
> +		 */
> +		if (cpu_addr > 0) {
> +			unsigned long nr_zeros = __ffs64(cpu_addr);
> +			u64 alignment = 1ULL << nr_zeros;
>  
> -		size = min(range->size, alignment);
> -	} else {
> -		size = range->size;
> -	}
> -	/* Hardware supports max 4GiB inbound region */
> -	size = min(size, 1ULL << 32);
> +			size = min(range->size, alignment);
> +		} else {
> +			size = range->size;
> +		}
> +		/* Hardware supports max 4GiB inbound region */
> +		size = min(size, 1ULL << 32);
>  
> -	mask = roundup_pow_of_two(size) - 1;
> -	mask &= ~0xf;
> +		mask = roundup_pow_of_two(size) - 1;
> +		mask &= ~0xf;
>  
> -	while (cpu_addr < cpu_end) {
>  		/*
>  		 * Set up 64-bit inbound regions as the range parser doesn't
>  		 * distinguish between 32 and 64-bit types.
> -- 
> 2.20.1
>