On 11/03/2014 10:13 AM, Thierry Reding wrote: > From: Thierry Reding <treding@xxxxxxxxxx> > > This commit introduces a new function, mipi_dsi_create_packet(), which > converts from a MIPI DSI message to a MIPI DSI packet. The MIPI DSI > packet is as close to the protocol described in the DSI specification as > possible and useful in drivers that need to write a DSI packet into a > FIFO to send a message off to the peripheral. > > Suggested-by: Andrzej Hajda <a.hajda@xxxxxxxxxxx> > Signed-off-by: Thierry Reding <treding@xxxxxxxxxx> > --- > drivers/gpu/drm/drm_mipi_dsi.c | 45 ++++++++++++++++++++++++++++++++++++++++++ > include/drm/drm_mipi_dsi.h | 18 +++++++++++++++++ > 2 files changed, 63 insertions(+) > > diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c > index eb6dfe52cab2..76e81aba8220 100644 > --- a/drivers/gpu/drm/drm_mipi_dsi.c > +++ b/drivers/gpu/drm/drm_mipi_dsi.c > @@ -199,6 +199,51 @@ int mipi_dsi_detach(struct mipi_dsi_device *dsi) > EXPORT_SYMBOL(mipi_dsi_detach); > > /** > + * mipi_dsi_create_packet - create a packet from a message according to the > + * DSI protocol > + * @packet: pointer to a DSI packet structure > + * @msg: message to translate into a packet > + * > + * Return: 0 on success or a negative error code on failure. > + */ > +int mipi_dsi_create_packet(struct mipi_dsi_packet *packet, > + const struct mipi_dsi_msg *msg) > +{ > + const u8 *tx = msg->tx_buf; > + > + if (!packet || !msg) > + return -EINVAL; > + > + memset(packet, 0, sizeof(*packet)); > + packet->header[0] = ((msg->channel & 0x3) << 6) | (msg->type & 0x3f); > + > + /* TODO: compute ECC if hardware support is not available */ > + > + /* > + * Long write packets contain the word count in header bytes 1 and 2. > + * The payload follows the header and is word count bytes long. > + * > + * Short write packets encode up to two parameters in header bytes 1 > + * and 2. > + */ > + if (msg->tx_len > 2) { This is incorrect, you can have long packet of payload length 0, look for "zero-byte Data Payload" phrase. I think you should check msg->type here. I have used: static bool exynos_dsi_is_short_dsi_type(u8 type) { return (type & 0x0f) <= 8; } quite ugly, but works :) > + packet->header[1] = (msg->tx_len >> 0) & 0xff; > + packet->header[2] = (msg->tx_len >> 8) & 0xff; > + > + packet->payload_length = msg->tx_len; > + packet->payload = tx; > + } else { > + packet->header[1] = (msg->tx_len > 0) ? tx[0] : 0; > + packet->header[2] = (msg->tx_len > 1) ? tx[1] : 0; > + } > + > + packet->size = sizeof(packet->header) + packet->payload_length; size seems to be completely useless. > + > + return 0; > +} > +EXPORT_SYMBOL(mipi_dsi_create_packet); > + > +/** > * mipi_dsi_dcs_write - send DCS write command > * @dsi: DSI device > * @data: pointer to the command followed by parameters > diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h > index 8569dc5a1026..663aa68826f4 100644 > --- a/include/drm/drm_mipi_dsi.h > +++ b/include/drm/drm_mipi_dsi.h > @@ -44,6 +44,24 @@ struct mipi_dsi_msg { > }; > > /** > + * struct mipi_dsi_packet - represents a MIPI DSI packet in protocol format > + * @size: size (in bytes) of the packet > + * @header: the four bytes that make up the header (Data ID, Word Count or > + * Packet Data, and ECC) > + * @payload_length: number of bytes in the payload > + * @payload: a pointer to a buffer containing the payload, if any > + */ > +struct mipi_dsi_packet { > + size_t size; > + u8 header[4]; I wonder if it wouldn't be good to make it u32 or at least anonymous union: union { u8 header[4]; u32 header32; }; And of course we should document its endiannes. This way we can use le16_to_cpu(pkt->header32) instead of constructing u32 value from array. Regards Andrzej > + size_t payload_length; > + const u8 *payload; > +}; > + > +int mipi_dsi_create_packet(struct mipi_dsi_packet *packet, > + const struct mipi_dsi_msg *msg); > + > +/** > * struct mipi_dsi_host_ops - DSI bus operations > * @attach: attach DSI device to DSI host > * @detach: detach DSI device from DSI host _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel