Messages in this thread | | | Date | Thu, 25 Oct 2018 00:52:39 +0200 | From | Boris Brezillon <> | Subject | Re: [PATCH v9 6/9] i3c: master: Add driver for Cadence IP |
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On Wed, 24 Oct 2018 17:43:00 -0500 Grygorii Strashko <grygorii.strashko@ti.com> wrote:
> On 10/24/18 4:04 PM, Boris Brezillon wrote: > > On Wed, 24 Oct 2018 15:25:17 -0500 > > Grygorii Strashko <grygorii.strashko@ti.com> wrote: > > > >> On 10/24/18 1:20 PM, Boris Brezillon wrote: > >>> Hi Arnd, > >>> > >>> On Mon, 22 Oct 2018 15:34:01 +0200 > >>> Boris Brezillon <boris.brezillon@bootlin.com> wrote: > >>> > >>> > >>>> + > >>>> +static void cdns_i3c_master_rd_from_rx_fifo(struct cdns_i3c_master *master, > >>>> + u8 *bytes, int nbytes) > >>>> +{ > >>>> + readsl(master->regs + RX_FIFO, bytes, nbytes / 4); > >>> > >>> Vitor reported a problem with readsl(): this function expects the 2nd > >>> argument to be aligned on 32-bit, which is not guaranteed here. Unless > >>> you see a better solution, I'll switch back to a loop doing: > >>> > >>> for (i = 0; i < nbytes; i += 4) { > >>> u32 tmp = __raw_readl(...); > >> > >> Pls, do not use __raw io. > > > > Except this is exactly what I want here, unless you have a > > replacement for "readl() without a mem-barrier and without endianness > > conversion" > > > > Not sure why endianness is the problem. readl_relaxed?
Because we want to read a stream of bytes, and, if we have a CPU that is operating in big-endian (ARM kernels can configured in BE or LE), byte ordering will be messed up (the controller is LE).
If I use readl_relaxed(), I'll then have to call cpu_to_le32(), and finally copy the result to the buffer.
> Sry, I've missed that this is part of the driver not i3c core, > so minor/ignore. >
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