Messages in this thread |  | | Date | Mon, 2 Apr 2018 22:32:32 +0200 | From | Boris Brezillon <> | Subject | Re: [PATCH] mtd: nand: raw: atmel: add module param to avoid using dma |
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On Mon, 2 Apr 2018 22:20:20 +0200 Boris Brezillon <boris.brezillon@bootlin.com> wrote:
> > > > > And > > > which DDR slave is the target? 7, 8, 9 or 10? More than one? > > > > This, I don't know. I guess all of them can be used. > > Looks like I was wrong. According to "Table 15-3. SAMA5D3 Master to > Slave Access", LCDC port 0 can only access DDR port 2 and LCDC port 1 > can only access DDR port 3. > > Can you try to write 0x3 to 0xFFFFECCC and 0x30 to 0xFFFFECD4? >
Oh, one more thing. Changing the priority won't necessarily solve your problem because of that:
" If more than one master requests the slave bus, regardless of the respective masters priorities, no master will be granted the slave bus for two consecutive runs. A master can only get back-to-back grants so long as it is the only requesting master. "
To solve that, you'll have to play with MATRIX_MCFGy.ULBT (make sure DMAC0 and DMAC1 have a small enough ULBT that is not 0) or MATRIX_SCFGx.SLOT_CYCLE (that one is probably harder to get right since it's expressed in AHB clock cycles).
-- Boris Brezillon, Bootlin (formerly Free Electrons) Embedded Linux and Kernel engineering https://bootlin.com
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