summaryrefslogtreecommitdiff
path: root/tools/gpio
diff options
context:
space:
mode:
authorSamuel Holland <samuel@sholland.org>2022-06-21 06:13:50 +0300
committerVinod Koul <vkoul@kernel.org>2022-07-05 16:04:26 +0300
commita94a098a21c678c07c8a742e4a65e8aa2bebdf08 (patch)
treeb20698645fb1366a620bf7324775567b088d668f /tools/gpio
parent9bef4929fa21477d44b4934d02296c4d0126dd40 (diff)
downloadlinux-a94a098a21c678c07c8a742e4a65e8aa2bebdf08.tar.xz
dmaengine: sun4i: Set the maximum segment size
The sun4i DMA engine supports transfer sizes up to 128k for normal DMA and 16M for dedicated DMA, as documented in the A10 and A20 manuals. Since this is larger than the default segment size limit (64k), exposing the real limit reduces the number of transfers needed for a transaction. However, because the device can only report one segment size limit, we have to expose the smaller limit from normal DMA. One complication is that the driver combines pairs of periodic transfers to reduce programming overhead. This only works when the period size is at most half of the maximum transfer size. With the default 64k segment size limit, this was always the case, but for normal DMA it is no longer guaranteed. Skip the optimization if the period is too long; even without it, the overhead is less than before. Signed-off-by: Samuel Holland <samuel@sholland.org> Link: https://lore.kernel.org/r/20220621031350.36187-1-samuel@sholland.org Signed-off-by: Vinod Koul <vkoul@kernel.org>
Diffstat (limited to 'tools/gpio')
0 files changed, 0 insertions, 0 deletions