From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932435AbdA3Pet (ORCPT ); Mon, 30 Jan 2017 10:34:49 -0500 Received: from mail-qk0-f182.google.com ([209.85.220.182]:34396 "EHLO mail-qk0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751752AbdA3PeI (ORCPT ); Mon, 30 Jan 2017 10:34:08 -0500 Date: Mon, 30 Jan 2017 10:26:11 -0500 From: Sean Paul To: John Keeping Cc: Mark Yao , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-rockchip@lists.infradead.org, Chris Zhong , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v3 24/24] drm/rockchip: dw-mipi-dsi: support read commands Message-ID: <20170130152611.GA20076@art_vandelay> References: <20170129132444.25251-1-john@metanate.com> <20170129132444.25251-25-john@metanate.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170129132444.25251-25-john@metanate.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jan 29, 2017 at 01:24:44PM +0000, John Keeping wrote: > I haven't found any method for getting the length of a response, so this > just uses the requested rx_len > > Signed-off-by: John Keeping > --- > v3: > - Fix checkpatch warnings > Unchanged in v2 > > drivers/gpu/drm/rockchip/dw-mipi-dsi.c | 56 ++++++++++++++++++++++++++++++++++ > 1 file changed, 56 insertions(+) > > diff --git a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c > index cf3ca6b0cbdb..cc58ada75425 100644 > --- a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c > +++ b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c > @@ -678,6 +678,56 @@ static int dw_mipi_dsi_dcs_long_write(struct dw_mipi_dsi *dsi, > return dw_mipi_dsi_gen_pkt_hdr_write(dsi, hdr_val); > } > > +static int dw_mipi_dsi_dcs_read(struct dw_mipi_dsi *dsi, > + const struct mipi_dsi_msg *msg) > +{ > + const u8 *tx_buf = msg->tx_buf; > + u8 *rx_buf = msg->rx_buf; > + size_t i; > + int ret, val; > + > + dsi_write(dsi, DSI_PCKHDL_CFG, EN_CRC_RX | EN_ECC_RX | EN_BTA); > + dsi_write(dsi, DSI_GEN_HDR, > + GEN_HDATA(tx_buf[0]) | GEN_HTYPE(msg->type)); > + > + ret = readl_poll_timeout(dsi->base + DSI_CMD_PKT_STATUS, > + val, !(val & GEN_RD_CMD_BUSY), 1000, > + CMD_PKT_STATUS_TIMEOUT_US); > + if (ret < 0) { > + dev_err(dsi->dev, "failed to read command response\n"); > + return ret; > + } > + > + for (i = 0; i < msg->rx_len;) { > + u32 pld = dsi_read(dsi, DSI_GEN_PLD_DATA); > + > + while (i < msg->rx_len) { > + rx_buf[i] = pld & 0xff; > + pld >>= 8; > + i++; > + } > + } AFAICT, the outer for loop just initializes i and ensures msg->rx_len is non-zero? I think the following would be easier to read (and safe against the case where msg->rx_len > sizeof(pld) (even though this shouldn't happen according to DCS spec)). if (msg->rx_len > 0) { u32 pld = dsi_read(dsi, DSI_GEN_PLD_DATA); memcpy(rx_buf, &pld, MIN(msg->rx_len, sizeof(pld)); } > + > + return msg->rx_len; > +} > + > +static int dw_mipi_dsi_set_max_return_packet_size(struct dw_mipi_dsi *dsi, > + size_t len) > +{ > + u8 val[] = { len & 0xff, (len >> 8) & 0xff }; > + struct mipi_dsi_msg msg = { > + .channel = dsi->channel, > + .type = MIPI_DSI_SET_MAXIMUM_RETURN_PACKET_SIZE, > + .tx_buf = val, > + .tx_len = 2, > + }; > + > + if (len > 0xffff) > + return -EINVAL; > + > + return dw_mipi_dsi_dcs_short_write(dsi, &msg); > +} > + > static ssize_t dw_mipi_dsi_host_transfer(struct mipi_dsi_host *host, > const struct mipi_dsi_msg *msg) > { > @@ -695,6 +745,12 @@ static ssize_t dw_mipi_dsi_host_transfer(struct mipi_dsi_host *host, > case MIPI_DSI_DCS_LONG_WRITE: > ret = dw_mipi_dsi_dcs_long_write(dsi, msg); > break; > + case MIPI_DSI_DCS_READ: > + ret = dw_mipi_dsi_set_max_return_packet_size(dsi, msg->rx_len); > + if (ret < 0) > + return ret; > + ret = dw_mipi_dsi_dcs_read(dsi, msg); > + break; > default: > dev_err(dsi->dev, "unsupported message type 0x%02x\n", > msg->type); > -- > 2.11.0.197.gb556de5.dirty > > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Sean Paul, Software Engineer, Google / Chromium OS