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authorViresh Kumar <viresh.kumar@st.com>2011-08-05 15:32:37 +0530
committerVinod Koul <vinod.koul@intel.com>2011-08-25 19:33:38 +0530
commit16a2e7d359b9fc64fb8a6717c0642691b1e60bb7 (patch)
treebfeea21d5b565a39ff32718327eb993d9b29c4aa /include/linux/amba
parent28da28365da3f3bea1d4b7212a8a40e4b9ac3229 (diff)
dmaengine/amba-pl08x: Get rid of pl08x_pre_boundary()
Pl080 Manual says: "Bursts do not cross the 1KB address boundary" We can program the controller to cross 1 KB boundary on a burst and controller can take care of this boundary condition by itself. Following is the discussion with ARM Technical Support Guys (David): [Viresh] Manual says: "Bursts do not cross the 1KB address boundary" What does that actually mean? As, Maximum size transferable with a single LLI is 4095 * 4 =16380 ~ 16KB. So, if we don't have src/dest address aligned to burst size, we can't use this big of an LLI. [David] There is a difference between bursts describing the total data transferred by the DMA controller and AHB bursts. Bursts described by the programmable parameters in the PL080 have no direct connection with the bursts that are seen on the AHB bus. The statement that "Bursts do not cross the 1KB address boundary" in the TRM is referring to AHB bursts, where this limitation is a requirement of the AHB spec. You can still issue bursts within the PL080 that are in excess of 1KB. The PL080 will make sure that its bursts are broken down into legal AHB bursts which will be formatted to ensure that no AHB burst crosses a 1KB boundary. Based on above discussion, this patch removes all code related to 1 KB boundary as we are not required to handle this in driver. Signed-off-by: Viresh Kumar <viresh.kumar@st.com> Acked-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Diffstat (limited to 'include/linux/amba')
-rw-r--r--include/linux/amba/pl08x.h2
1 files changed, 0 insertions, 2 deletions
diff --git a/include/linux/amba/pl08x.h b/include/linux/amba/pl08x.h
index cd8f629da58..ecd17f581e7 100644
--- a/include/linux/amba/pl08x.h
+++ b/include/linux/amba/pl08x.h
@@ -77,13 +77,11 @@ struct pl08x_channel_data {
* @addr: current address
* @maxwidth: the maximum width of a transfer on this bus
* @buswidth: the width of this bus in bytes: 1, 2 or 4
- * @fill_bytes: bytes required to fill to the next bus memory boundary
*/
struct pl08x_bus_data {
dma_addr_t addr;
u8 maxwidth;
u8 buswidth;
- size_t fill_bytes;
};
/**