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[24.22.235.96]) by smtp.gmail.com with ESMTPSA id o76sm16154476pfa.156.2019.03.21.20.29.22 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 21 Mar 2019 20:29:23 -0700 (PDT) From: Andrey Smirnov To: dri-devel@lists.freedesktop.org Cc: Andrey Smirnov , Archit Taneja , Andrzej Hajda , Laurent Pinchart , Tomi Valkeinen , Andrey Gusakov , Philipp Zabel , Chris Healy , Lucas Stach , linux-kernel@vger.kernel.org Subject: [PATCH v2 07/15] drm/bridge: tc358767: Simplify AUX data write Date: Thu, 21 Mar 2019 20:28:53 -0700 Message-Id: <20190322032901.12045-8-andrew.smirnov@gmail.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190322032901.12045-1-andrew.smirnov@gmail.com> References: <20190322032901.12045-1-andrew.smirnov@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Cc: Archit Taneja Cc: Andrzej Hajda Cc: Laurent Pinchart Cc: Tomi Valkeinen Cc: Andrey Gusakov Cc: Philipp Zabel Cc: Chris Healy Cc: Lucas Stach 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); + + 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])); + if (ret) + return ret; + } + + return size; +} + static int tc_aux_read_data(struct tc_data *tc, void *data, size_t size) { u32 auxrdata[DP_AUX_MAX_PAYLOAD_BYTES / sizeof(u32)]; @@ -335,9 +360,6 @@ static ssize_t tc_aux_transfer(struct drm_dp_aux *aux, struct tc_data *tc = aux_to_tc(aux); size_t size = min_t(size_t, 8, msg->size); u8 request = msg->request & ~DP_AUX_I2C_MOT; - u8 *buf = msg->buffer; - u32 tmp = 0; - int i = 0; int ret; if (size == 0) @@ -347,25 +369,17 @@ static ssize_t tc_aux_transfer(struct drm_dp_aux *aux, if (ret) return ret; - if (request == DP_AUX_I2C_WRITE || request == DP_AUX_NATIVE_WRITE) { - /* Store data */ - while (i < size) { - if (request == DP_AUX_NATIVE_WRITE) - tmp = tmp | (buf[i] << (8 * (i & 0x3))); - else - tmp = (tmp << 8) | buf[i]; - i++; - if (((i % 4) == 0) || (i == size)) { - ret = regmap_write(tc->regmap, - DP0_AUXWDATA((i - 1) >> 2), - tmp); - if (ret) - return ret; - tmp = 0; - } - } - } else if (request != DP_AUX_I2C_READ && - request != DP_AUX_NATIVE_READ) { + switch (request) { + case DP_AUX_NATIVE_READ: + case DP_AUX_I2C_READ: + break; + case DP_AUX_NATIVE_WRITE: + case DP_AUX_I2C_WRITE: + ret = tc_aux_write_data(tc, msg->buffer, size); + if (ret < 0) + return ret; + break; + default: return -EINVAL; } -- 2.20.1