Re: [PATCH net-next 2/4] net: ipa: introduce dma_addr_high32()
From: Florian Fainelli <f.fainelli@gmail.com>
Date: 2021-03-17 22:48:47
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lkml
On 3/17/2021 3:29 PM, Alex Elder wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- 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...
quoted hunk ↗ jump to hunk
+#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?
quoted hunk ↗ jump to hunk
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