On Tue, Jul 09, 2019 at 03:15:59AM +0200, marek.vasut@xxxxxxxxx wrote:
> From: Marek Vasut <marek.vasut+renesas@xxxxxxxxx>
>
> 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@xxxxxxxxx>
> Cc: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
> Cc: Wolfram Sang <wsa@xxxxxxxxxxxxx>
> Cc: linux-renesas-soc@xxxxxxxxxxxxxxx
> To: linux-pci@xxxxxxxxxxxxxxx
Reviewed-by: Simon Horman <horms+renesas@xxxxxxxxxxxx>
> ---
> 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
>
