From fdb29b738017672069f95747c48eac947b9beba2 Mon Sep 17 00:00:00 2001 From: Andrey Smirnov Date: Tue, 18 Jun 2019 22:27:16 -0700 Subject: [PATCH] drm/bridge: tc358767: Add support for address-only I2C transfers Transfer size of zero means a request to do an address-only transfer. Since the HW support this, we probably shouldn't be just ignoring such requests. While at it allow DP_AUX_I2C_MOT flag to pass through, since it is supported by the HW as well. Signed-off-by: Andrey Smirnov Reviewed-by: Andrzej Hajda Reviewed-by: Tomi Valkeinen Cc: Andrzej Hajda Cc: Laurent Pinchart Cc: Tomi Valkeinen Cc: Andrey Gusakov Cc: Philipp Zabel Cc: Cory Tusar Cc: Chris Healy Cc: Lucas Stach Cc: dri-devel@lists.freedesktop.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Andrzej Hajda Link: https://patchwork.freedesktop.org/patch/msgid/20190619052716.16831-16-andrew.smirnov@gmail.com --- drivers/gpu/drm/bridge/tc358767.c | 42 +++++++++++++++++++++++++++++---------- 1 file changed, 31 insertions(+), 11 deletions(-) diff --git a/drivers/gpu/drm/bridge/tc358767.c b/drivers/gpu/drm/bridge/tc358767.c index 38f15e740b70..e1ce4954e6af 100644 --- a/drivers/gpu/drm/bridge/tc358767.c +++ b/drivers/gpu/drm/bridge/tc358767.c @@ -136,6 +136,8 @@ /* AUX channel */ #define DP0_AUXCFG0 0x0660 +#define DP0_AUXCFG0_BSIZE GENMASK(11, 8) +#define DP0_AUXCFG0_ADDR_ONLY BIT(4) #define DP0_AUXCFG1 0x0664 #define AUX_RX_FILTER_EN BIT(16) @@ -317,6 +319,18 @@ static int tc_aux_read_data(struct tc_data *tc, void *data, size_t size) return size; } +static u32 tc_auxcfg0(struct drm_dp_aux_msg *msg, size_t size) +{ + u32 auxcfg0 = msg->request; + + if (size) + auxcfg0 |= FIELD_PREP(DP0_AUXCFG0_BSIZE, size - 1); + else + auxcfg0 |= DP0_AUXCFG0_ADDR_ONLY; + + return auxcfg0; +} + static ssize_t tc_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg) { @@ -326,9 +340,6 @@ static ssize_t tc_aux_transfer(struct drm_dp_aux *aux, u32 auxstatus; int ret; - if (size == 0) - return 0; - ret = tc_aux_wait_busy(tc); if (ret) return ret; @@ -339,9 +350,11 @@ static ssize_t tc_aux_transfer(struct drm_dp_aux *aux, 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; + if (size) { + ret = tc_aux_write_data(tc, msg->buffer, size); + if (ret < 0) + return ret; + } break; default: return -EINVAL; @@ -352,8 +365,7 @@ static ssize_t tc_aux_transfer(struct drm_dp_aux *aux, if (ret) return ret; /* Start transfer */ - ret = regmap_write(tc->regmap, DP0_AUXCFG0, - ((size - 1) << 8) | request); + ret = regmap_write(tc->regmap, DP0_AUXCFG0, tc_auxcfg0(msg, size)); if (ret) return ret; @@ -367,14 +379,22 @@ static ssize_t tc_aux_transfer(struct drm_dp_aux *aux, if (auxstatus & AUX_TIMEOUT) return -ETIMEDOUT; - - size = FIELD_GET(AUX_BYTES, auxstatus); + /* + * For some reason address-only DP_AUX_I2C_WRITE (MOT), still + * reports 1 byte transferred in its status. To deal we that + * we ignore aux_bytes field if we know that this was an + * address-only transfer + */ + if (size) + size = FIELD_GET(AUX_BYTES, auxstatus); msg->reply = FIELD_GET(AUX_STATUS, auxstatus); switch (request) { case DP_AUX_NATIVE_READ: case DP_AUX_I2C_READ: - return tc_aux_read_data(tc, msg->buffer, size); + if (size) + return tc_aux_read_data(tc, msg->buffer, size); + break; } return size; -- 2.11.0