cpu/nrf52840: fix UART DMA when data is in ROM#11170
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jcarrano merged 1 commit intoRIOT-OS:masterfrom Mar 13, 2019
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haukepetersen
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Type: bug
jcarrano
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Mar 13, 2019
| * So if the given `data` buffer resides in ROM, we need to copy it to RAM | ||
| * before being able to transfer it. To make sure the stack does not | ||
| * overflow, we do this chunk-wise. */ | ||
| if (!((uint32_t)data & RAM_MASK)) { |
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| if (!((uint32_t)data & RAM_MASK)) { | |
| if (!((intptr_t)data & RAM_MASK)) { |
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Contribution description
When testing #11096, we discovered a bug in the
nrf5240s uart implementation: Nordic'sEasyDMAis only capable of transferring data from RAM, but not from ROM. So whenever passing a ROM location to the UART driver (e.g. someconst char *), the UART would only transfer0x00bytes. This made e.g.tests/fmt_printfail for all targets using thenrf5280cpu.This PR fixes this issue by chunk-wise copying the TX data into RAM before sending it in case the data is coming from ROM.
Testing procedure
Run e.g. the
tests/fmt_printtest on thenrf52840dkor thereelor similar. Without this PR the test will fail, with this PR it will succeed.Issues/PRs references
issue found in #11096