On Fri, May 15, 2020 at 01:47:48PM +0300, Serge Semin wrote:

It isn't good to have numeric literals in the code especially if there
are multiple of them and they are related. Moreover in current
implementation the Tx DMA transfer activation level isn't optimal,
since it's hardwired to be at 16-32 bytes level, while it's better
to keep the SPI FIFO buffer as full as possible until all available
data is submitted. So lets introduce the DMA burst level
parametrization macros with optimal values - issue Rx transfer if at
least 16 bytes are available in the buffer and execute Tx transaction
if at least 16 bytes room is opened in SPI Tx FIFO.

-	dw_writel(dws, DW_SPI_DMARDLR, 0xf);
-	dw_writel(dws, DW_SPI_DMATDLR, 0x10);
+	dw_writel(dws, DW_SPI_DMARDLR, RX_BURST_LEVEL - 1);
+	dw_writel(dws, DW_SPI_DMATDLR, dws->fifo_len - TX_BURST_LEVEL);

...and if FIFO length is less than TX_BURST_LEVEL?

For the patch that introduces definitions, i.e. keeping the last line here as

	dw_writel(dws, DW_SPI_DMATDLR, TX_BURST_LEVEL);

I'm good. You may put your tag in that case. For fifo_len case we need to
discuss in separate patch, perhaps.

-- 
With Best Regards,
Andy Shevchenko