Hi Andy,
andriy.shevchenko@xxxxxxxxxxxxxxx wrote on Fri, 18 Mar 2022 16:24:51
+0200:
> On Thu, Mar 17, 2022 at 06:46:25PM +0100, Miquel Raynal wrote:
> > From: Phil Edworthy <phil.edworthy@xxxxxxxxxxx>
> >
> > DW based controllers like the one on Renesas RZ/N1 must be programmed as
> > flow controllers when using DMA.
> >
> > * Table 11.45 of the system manual, "Flow Control Combinations", states
> > that using UART with DMA requires setting the DMA in the peripheral
> > flow controller mode regardless of the direction.
> >
> > * Chapter 11.6.1.3 of the system manual, "Basic Interface Definitions",
> > explains that the burst size in the above case must be configured in
> > the peripheral's register DEST/SRC_BURST_SIZE.
> >
> > Experiments shown that upon Rx timeout, the DMA transaction needed to be
> > manually cleared as well.
>
> ...
>
> > +#define DW_UART_TDMACR 0x10c /* DMA Control Register Transmit Mode */
> > +#define DW_UART_RDMACR 0x110 /* DMA Control Register Receive Mode */
>
> These are not Synposys ones.
Ok
> ...
>
> > +static u32 dw8250_rzn1_get_dmacr_burst(int max_burst)
> > +{
> > + if (max_burst >= 8)
> > + return DW_UART_xDMACR_8_WORD_BURST;
> > + else if (max_burst >= 4)
> > + return DW_UART_xDMACR_4_WORD_BURST;
> > + else
> > + return DW_UART_xDMACR_1_WORD_BURST;
> > +}
>
> Redundant 'else' in all cases.
I'm sorry but dropping the else statement here does not make any
sense. I find it much easier to the eyes the current way.
Thanks,
Miquèl
