From 39eb7e0e8c88dee58f83df8aa9f7a58559fa45ee Mon Sep 17 00:00:00 2001 From: =?utf8?q?Bj=C3=B8rn=20Mork?= Date: Fri, 30 May 2014 09:31:09 +0200 Subject: [PATCH] net: cdc_ncm: allow tuning min_tx_pkt MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The min_tx_pkt variable decides the cutoff point where the driver will stop padding out NTBs to maximum size. The padding is a tradeoff where we use some USB bus bandwidth to allow the device to receive fixed size buffers. Different devices will have different optimal settings, spanning from no padding at all to padding every NTB. There is no way to automatically figure out which setting is best for a specific device. The default value is a reasonable tradeoff, calculated based on the USB packet size and out NTB max size. This may have to be changed along with any tx_max changes. Signed-off-by: Bjørn Mork Signed-off-by: David S. Miller --- drivers/net/usb/cdc_ncm.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c index 98c3adb5aea3..80a844e0ae03 100644 --- a/drivers/net/usb/cdc_ncm.c +++ b/drivers/net/usb/cdc_ncm.c @@ -185,6 +185,14 @@ static u32 cdc_ncm_check_tx_max(struct usbnet *dev, u32 new_tx) return val; } +static ssize_t cdc_ncm_show_min_tx_pkt(struct device *d, struct device_attribute *attr, char *buf) +{ + struct usbnet *dev = netdev_priv(to_net_dev(d)); + struct cdc_ncm_ctx *ctx = (struct cdc_ncm_ctx *)dev->data[0]; + + return sprintf(buf, "%u\n", ctx->min_tx_pkt); +} + static ssize_t cdc_ncm_show_rx_max(struct device *d, struct device_attribute *attr, char *buf) { struct usbnet *dev = netdev_priv(to_net_dev(d)); @@ -209,6 +217,20 @@ static ssize_t cdc_ncm_show_tx_timer_usecs(struct device *d, struct device_attri return sprintf(buf, "%u\n", ctx->timer_interval / (u32)NSEC_PER_USEC); } +static ssize_t cdc_ncm_store_min_tx_pkt(struct device *d, struct device_attribute *attr, const char *buf, size_t len) +{ + struct usbnet *dev = netdev_priv(to_net_dev(d)); + struct cdc_ncm_ctx *ctx = (struct cdc_ncm_ctx *)dev->data[0]; + unsigned long val; + + /* no need to restrict values - anything from 0 to infinity is OK */ + if (kstrtoul(buf, 0, &val)) + return -EINVAL; + + ctx->min_tx_pkt = val; + return len; +} + static ssize_t cdc_ncm_store_rx_max(struct device *d, struct device_attribute *attr, const char *buf, size_t len) { struct usbnet *dev = netdev_priv(to_net_dev(d)); @@ -256,6 +278,7 @@ static ssize_t cdc_ncm_store_tx_timer_usecs(struct device *d, struct device_att return len; } +static DEVICE_ATTR(min_tx_pkt, S_IRUGO | S_IWUSR, cdc_ncm_show_min_tx_pkt, cdc_ncm_store_min_tx_pkt); static DEVICE_ATTR(rx_max, S_IRUGO | S_IWUSR, cdc_ncm_show_rx_max, cdc_ncm_store_rx_max); static DEVICE_ATTR(tx_max, S_IRUGO | S_IWUSR, cdc_ncm_show_tx_max, cdc_ncm_store_tx_max); static DEVICE_ATTR(tx_timer_usecs, S_IRUGO | S_IWUSR, cdc_ncm_show_tx_timer_usecs, cdc_ncm_store_tx_timer_usecs); @@ -281,6 +304,7 @@ NCM_PARM_ATTR(wNdpOutAlignment, "%u", le16_to_cpu); NCM_PARM_ATTR(wNtbOutMaxDatagrams, "%u", le16_to_cpu); static struct attribute *cdc_ncm_sysfs_attrs[] = { + &dev_attr_min_tx_pkt.attr, &dev_attr_rx_max.attr, &dev_attr_tx_max.attr, &dev_attr_tx_timer_usecs.attr, -- 2.34.1