Messages in this thread | | | From | Andrey Smirnov <> | Date | Fri, 22 Mar 2019 10:25:22 -0700 | Subject | Re: [PATCH v2 07/15] drm/bridge: tc358767: Simplify AUX data write |
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On Fri, Mar 22, 2019 at 3:51 AM Tomi Valkeinen <tomi.valkeinen@ti.com> wrote: > > On 22/03/2019 05:28, Andrey Smirnov wrote: > > Simplify AUX data write by dropping index arithmetic and shifting and > > replacing it with a call to a helper function that does three things: > > > > 1. Copies user-provided data into a write buffer > > 2. Optionally fixes the endianness of the write buffer (not needed > > on LE hosts) > > 3. Transfers contenst of the write buffer to up to 4 32-bit > > registers on the chip > > > > Note that separate data endianness fix: > > > > tmp = (tmp << 8) | buf[i]; > > > > that was reserved for DP_AUX_I2C_WRITE looks really strange, since it > > will place data differently depending on the passed user-data > > size. E.g. for a write of 1 byte, data transferred to the chip would > > look like: > > > > [byte0] [dummy1] [dummy2] [dummy3] > > > > whereas for a write of 4 bytes we'd get: > > > > [byte3] [byte2] [byte1] [byte0] > > > > Since there's no indication in the datasheet that I2C write buffer > > should be treated differently than AUX write buffer and no comment in > > the original code explaining why it was done this way, that special > > I2C write buffer transformation was dropped in this patch. > > > > Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com> > > Cc: Archit Taneja <architt@codeaurora.org> > > Cc: Andrzej Hajda <a.hajda@samsung.com> > > Cc: Laurent Pinchart <Laurent.pinchart@ideasonboard.com> > > Cc: Tomi Valkeinen <tomi.valkeinen@ti.com> > > Cc: Andrey Gusakov <andrey.gusakov@cogentembedded.com> > > Cc: Philipp Zabel <p.zabel@pengutronix.de> > > Cc: Chris Healy <cphealy@gmail.com> > > Cc: Lucas Stach <l.stach@pengutronix.de> > > Cc: dri-devel@lists.freedesktop.org > > Cc: linux-kernel@vger.kernel.org > > --- > > drivers/gpu/drm/bridge/tc358767.c | 58 +++++++++++++++++++------------ > > 1 file changed, 36 insertions(+), 22 deletions(-) > > > > diff --git a/drivers/gpu/drm/bridge/tc358767.c b/drivers/gpu/drm/bridge/tc358767.c > > index 81c10a5d8106..21374565585d 100644 > > --- a/drivers/gpu/drm/bridge/tc358767.c > > +++ b/drivers/gpu/drm/bridge/tc358767.c > > @@ -307,6 +307,31 @@ static int tc_aux_get_status(struct tc_data *tc, u8 *reply) > > return 0; > > } > > > > +static int tc_aux_write_data(struct tc_data *tc, const void *data, > > + size_t size) > > +{ > > + u32 auxwdata[DP_AUX_MAX_PAYLOAD_BYTES / sizeof(u32)] = { 0 }; > > + int ret, i, count = DIV_ROUND_UP(size, 4); > > Should 4 there be sizeof(u32)?
Yup, will replace.
> > > + > > + memcpy(auxwdata, data, size); > > + > > + for (i = 0; i < count; i++) { > > + ret = regmap_write(tc->regmap, DP0_AUXWDATA(i), > > + /* > > + * Our regmap is configured as LE > > + * for register data, so we need > > + * undo any byte swapping that will > > + * happened to preserve original > > + * byte order. > > + */ > > + cpu_to_le32(auxwdata[i])); > > Can regmap_bulk_write or regmap_raw_write be used here? >
Not sure, will give it a try.
Thanks, Andrey Smirnov
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