On 3/17/2021 3:29 PM, Alex Elder wrote:
> Create a new helper function to encapsulate extracting the
> high-order 32 bits of a DMA address. It returns 0 for builds
> in which a DMA address is not 64 bits.
>
> This avoids doing a 32-position shift on a DMA address if it
> happens not to be 64 bits wide.
>
> Signed-off-by: Alex Elder <el...@linaro.org>
> ---
> drivers/net/ipa/gsi.c | 14 ++++++++++++--
> 1 file changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/ipa/gsi.c b/drivers/net/ipa/gsi.c
> index 2119367b93ea9..53698c64cf882 100644
> --- a/drivers/net/ipa/gsi.c
> +++ b/drivers/net/ipa/gsi.c
> @@ -688,6 +688,16 @@ static void gsi_evt_ring_doorbell(struct gsi *gsi, u32
> evt_ring_id, u32 index)
> iowrite32(val, gsi->virt + GSI_EV_CH_E_DOORBELL_0_OFFSET(evt_ring_id));
> }
>
> +/* Encapsulate extracting high-order 32 bits of DMA address */
> +static u32 dma_addr_high32(dma_addr_t addr)
> +{
> +#ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT
> + return (u32)(addr >> 32);
You can probably use upper_32bits() here...
> +#else /* !CONFIG_ARCH_DMA_ADDR_T_64BIT */
> + return 0;
> +#endif /* !CONFIG_ARCH_DMA_ADDR_T_64BIT */
> +}
> +
> /* Program an event ring for use */
> static void gsi_evt_ring_program(struct gsi *gsi, u32 evt_ring_id)
> {
> @@ -711,7 +721,7 @@ static void gsi_evt_ring_program(struct gsi *gsi, u32
> evt_ring_id)
> val = evt_ring->ring.addr & GENMASK(31, 0);
...and you can use lower_32bits() here.
> iowrite32(val, gsi->virt + GSI_EV_CH_E_CNTXT_2_OFFSET(evt_ring_id));
>
> - val = evt_ring->ring.addr >> 32;
> + val = dma_addr_high32(evt_ring->ring.addr);
Does the compiler do a good job at eliminating the assignment when
CONFIG_ARCH_DMA_ADDR_T_64BIT is not defined?
> iowrite32(val, gsi->virt + GSI_EV_CH_E_CNTXT_3_OFFSET(evt_ring_id));
>
> /* Enable interrupt moderation by setting the moderation delay */
> @@ -819,7 +829,7 @@ static void gsi_channel_program(struct gsi_channel
> *channel, bool doorbell)
> val = channel->tre_ring.addr & GENMASK(31, 0);
> iowrite32(val, gsi->virt + GSI_CH_C_CNTXT_2_OFFSET(channel_id));
>
> - val = channel->tre_ring.addr >> 32;
> + val = dma_addr_high32(channel->tre_ring.addr);
> iowrite32(val, gsi->virt + GSI_CH_C_CNTXT_3_OFFSET(channel_id));
>
> /* Command channel gets low weighted round-robin priority */
>
--
Florian
