On Wed 2018-10-10 19:09:36, Lubomir Rintel wrote: > There doesn't seem to be a way to empty TXFIFO on MMP2. The datasheet is > super-secret and the method described in Armada 16x manual won't work: > > "The TXFIFO and RXFIFO are cleared to 0b0 when the SSPx port is reset or > disabled (by writing a 0b0 to the <Synchronous Serial Port Enable> field > in the SSP Control Register 0)." > > # devmem 0xd4037008 # read SSSR > 0x0000F204 > # devmem 0xd4037000 32 0x80 # SSE off in SSCR0 > # devmem 0xd4037000 32 0x87 # SSE on > # devmem 0xd4037008 > 0x0000F204 > ^ TXFIFO level is still 2. Sigh. > > The OLPC 1.75 boot firmware leaves two bytes in the TXFIFO. Those are > basically throwaway bytes used in response to the messages from the EC. > The OLPC kernel copes with this by power-cycling the hardware. Perhaps > the firmware should do this instead. > > Other than that, there's not much we can do other than complain loudly > until the garbage gets drained and discard the actual data... For the > OLPC EC this will work just fine and pushing more data to TXFIFO would > break further transactions. > > Signed-off-by: Lubomir Rintel <lkundrak@xxxxx> Acked-by: Pavel Machek <pavel@xxxxxx> -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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