Messages in this thread Patch in this message | | | Date | Tue, 11 Oct 2011 10:55:28 -0600 | From | Greg KH <> | Subject | [18/38] drm/radeon/kms: add retry limits for native DP aux defer |
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3.0-stable review patch. If anyone has any objections, please let us know.
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From: Alex Deucher <alexander.deucher@amd.com>
commit 6375bda073724ead7df08746866b724b1799a295 upstream.
The previous code could potentially loop forever. Limit the number of DP aux defer retries to 4 for native aux transactions, same as i2c over aux transactions.
Noticed by: Brad Campbell <lists2009@fnarfbargle.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com> Cc: Brad Campbell <lists2009@fnarfbargle.com> Signed-off-by: Dave Airlie <airlied@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- drivers/gpu/drm/radeon/atombios_dp.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-)
--- a/drivers/gpu/drm/radeon/atombios_dp.c +++ b/drivers/gpu/drm/radeon/atombios_dp.c @@ -115,6 +115,7 @@ static int radeon_dp_aux_native_write(st u8 msg[20]; int msg_bytes = send_bytes + 4; u8 ack; + unsigned retry; if (send_bytes > 16) return -1; @@ -125,20 +126,20 @@ static int radeon_dp_aux_native_write(st msg[3] = (msg_bytes << 4) | (send_bytes - 1); memcpy(&msg[4], send, send_bytes); - while (1) { + for (retry = 0; retry < 4; retry++) { ret = radeon_process_aux_ch(dig_connector->dp_i2c_bus, msg, msg_bytes, NULL, 0, delay, &ack); if (ret < 0) return ret; if ((ack & AUX_NATIVE_REPLY_MASK) == AUX_NATIVE_REPLY_ACK) - break; + return send_bytes; else if ((ack & AUX_NATIVE_REPLY_MASK) == AUX_NATIVE_REPLY_DEFER) udelay(400); else return -EIO; } - return send_bytes; + return -EIO; } static int radeon_dp_aux_native_read(struct radeon_connector *radeon_connector, @@ -149,13 +150,14 @@ static int radeon_dp_aux_native_read(str int msg_bytes = 4; u8 ack; int ret; + unsigned retry; msg[0] = address; msg[1] = address >> 8; msg[2] = AUX_NATIVE_READ << 4; msg[3] = (msg_bytes << 4) | (recv_bytes - 1); - while (1) { + for (retry = 0; retry < 4; retry++) { ret = radeon_process_aux_ch(dig_connector->dp_i2c_bus, msg, msg_bytes, recv, recv_bytes, delay, &ack); if (ret < 0) @@ -169,6 +171,8 @@ static int radeon_dp_aux_native_read(str else return -EIO; } + + return -EIO; } static void radeon_write_dpcd_reg(struct radeon_connector *radeon_connector,
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