Re: [PATCH] mcp23s08: support mcp23s17 variant

[Peter Korsgaard]

>>>>> "Grant" == Grant Likely <grant.likely@xxxxxxxxxxxx> writes:

Hi,

 >> - Â Â Â return (status < 0) ? status : rx[0];
 >> +
 >> + Â Â Â if (mcp->type == MCP_TYPE_S17) {
 >> + Â Â Â Â Â Â Â tx[1] <<= 1;
 >> +
 >> + Â Â Â Â Â Â Â status = spi_write_then_read(mcp->spi, tx, sizeof tx, rx, 2);
 >> + Â Â Â Â Â Â Â return (status < 0) ? status : (rx[0] | (rx[1] << 8));
 >> + Â Â Â } else {
 >> + Â Â Â Â Â Â Â status = spi_write_then_read(mcp->spi, tx, sizeof tx, rx, 1);
 >> + Â Â Â Â Â Â Â return (status < 0) ? status : rx[0];
 >> + Â Â Â }

 Grant> Rather than checking ->type for every transaction, would a set of
 Grant> callbacks for each type be better?  It would probably have lower
 Grant> overhead and be simpler to maintain.

We could. I didn't do it because the 8bit and 16bit cases are very
similar, and checking a simple integer is presumably a lot faster than
the spi access - But I can rework the patch if you insists.

 >> +++ b/include/linux/spi/mcp23s08.h
 >> @@ -2,21 +2,24 @@
 >> Â/* FIXME driver should be able to handle IRQs... Â*/
 >> 
 >> Âstruct mcp23s08_chip_info {
 >> -    bool  Âis_present;       /* true iff populated */
 >> - Â Â Â u8 Â Â Âpullups; Â Â Â Â Â Â Â Â/* BIT(x) means enable pullup x */
 >> +    bool      Âis_present;   /* true if populated */
 >> +    unsigned    Âpullups;    Â/* BIT(x) means enable pullup x */
 >> Â};

 Grant> Unrelated whitespace changes.

I wouldn't call it unrelated. It's to ensure it still lines up after the
s/u8/unsigned/.

-- 
Bye, Peter Korsgaard
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