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tty: n_gsm: Fix SOF skipping 

[ Upstream commit 84d6f81c1f ]

For at least some modems like the TELIT LE910, skipping SOF makes
transfers blocking indefinitely after a short amount of data
transferred.

Given the small improvement provided by skipping the SOF (just one
byte on about 100 bytes), it seems better to completely remove this
"feature" than make it optional.

Fixes: e1eaea46bb ("tty: n_gsm line discipline")
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Link: https://lore.kernel.org/r/20200512115323.1447922-3-gregory.clement@bootlin.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Gregory CLEMENT 2020-05-12 13:53:22 +02:00 committed by Greg Kroah-Hartman
parent 7fcc2ca6a3
commit 3a497f97a3
1 changed files with 1 additions and 7 deletions
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8
drivers/tty/n_gsm.c
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@ -669,7 +669,6 @@ static void gsm_data_kick(struct gsm_mux *gsm)
{
struct gsm_msg *msg, *nmsg;
int len;
int skip_sof = 0;
list_for_each_entry_safe(msg, nmsg, &gsm->tx_list, list) {
if (gsm->constipated && msg->addr)
@ -691,15 +690,10 @@ static void gsm_data_kick(struct gsm_mux *gsm)
print_hex_dump_bytes("gsm_data_kick: ",
DUMP_PREFIX_OFFSET,
gsm->txframe, len);
if (gsm->output(gsm, gsm->txframe + skip_sof,
len - skip_sof) < 0)
if (gsm->output(gsm, gsm->txframe, len) < 0)
break;
/* FIXME: Can eliminate one SOF in many more cases */
gsm->tx_bytes -= msg->len;
/* For a burst of frames skip the extra SOF within the
burst */
skip_sof = 1;
list_del(&msg->list);
kfree(msg);