Re: [PATCH v1 RFC 1/1] Add Microchip KSZ8795 DSA driver

From: Pavel Machek
Date: Wed Oct 11 2017 - 16:59:25 EST


Hi!

> +static void ksz8795_set_prio_queue(struct ksz_device *dev, int port, int queue)
> +{
> + u8 hi;
> + u8 lo;
> +
> + /* Number of queues can only be 1, 2, or 4. */
> + switch (queue) {
> + case 4:
> + case 3:
> + queue = PORT_QUEUE_SPLIT_4;
> + break;
> + case 2:
> + queue = PORT_QUEUE_SPLIT_2;
> + break;
> + default:
> + queue = PORT_QUEUE_SPLIT_1;
> + }

If only 1, 2 and 4 are valid, it probably should not accept other
values?

> +static void ksz8795_r_mib_cnt(struct ksz_device *dev, int port, u16 addr,
> + u64 *cnt)
> +{
> + u32 data;
> + u16 ctrl_addr;
> + u8 check;
> + int loop;
> +
> + ctrl_addr = addr + SWITCH_COUNTER_NUM * port;
> + ctrl_addr |= IND_ACC_TABLE(TABLE_MIB | TABLE_READ);
> +
> + mutex_lock(&dev->alu_mutex);
> + ksz_write16(dev, REG_IND_CTRL_0, ctrl_addr);
> +
> + /* It is almost guaranteed to always read the valid bit because of
> + * slow SPI speed.
> + */
> + for (loop = 2; loop > 0; loop--) {
> + ksz_read8(dev, REG_IND_MIB_CHECK, &check);
> +
> + if (check & MIB_COUNTER_VALID) {
> + ksz_read32(dev, REG_IND_DATA_LO, &data);
> + if (check & MIB_COUNTER_OVERFLOW)
> + *cnt += MIB_COUNTER_VALUE + 1;
> + *cnt += data & MIB_COUNTER_VALUE;
> + break;
> + }
> + }

Hmm. Maybe, but should not this at least warn if if it can not get
valid counter?

> + /* It is almost guaranteed to always read the valid bit because of
> + * slow SPI speed.
> + */
> + for (loop = 2; loop > 0; loop--) {
> + ksz_read8(dev, REG_IND_MIB_CHECK, &check);
> +
> + if (check & MIB_COUNTER_VALID) {
> + ksz_read32(dev, REG_IND_DATA_LO, &data);
> + if (addr < 2) {
> + u64 total;
> +
> + total = check & MIB_TOTAL_BYTES_H;
> + total <<= 32;
> + *cnt += total;
> + *cnt += data;
> + if (check & MIB_COUNTER_OVERFLOW) {
> + total = MIB_TOTAL_BYTES_H + 1;
> + total <<= 32;
> + *cnt += total;
> + }
> + } else {
> + if (check & MIB_COUNTER_OVERFLOW)
> + *cnt += MIB_PACKET_DROPPED + 1;
> + *cnt += data & MIB_PACKET_DROPPED;
> + }
> + break;
> + }
> + }

Same here. Plus, is overflow handling correct? There may be more than
MIB_PACKET_DROPPED + 1 packets dropped between the checks.

> +static void ksz8795_r_table(struct ksz_device *dev, int table, u16 addr,
> + u64 *data)
> +{
> + u16 ctrl_addr;
> +
> + ctrl_addr = IND_ACC_TABLE(table | TABLE_READ) | addr;
> +
> + mutex_lock(&dev->alu_mutex);
> + ksz_write16(dev, REG_IND_CTRL_0, ctrl_addr);
> + ksz_get(dev, REG_IND_DATA_HI, data, sizeof(u64));
> + mutex_unlock(&dev->alu_mutex);
> + *data = be64_to_cpu(*data);
> +}

It would be a tiny bit nicer to have be64 temporary variable and use
it; having *data change endianness at runtime is "interesting".

> +static int ksz8795_valid_dyn_entry(struct ksz_device *dev, u8 *data)
> +{
> + int timeout = 100;
> +
> + do {
> + ksz_read8(dev, REG_IND_DATA_CHECK, data);
> + timeout--;
> + } while ((*data & DYNAMIC_MAC_TABLE_NOT_READY) && timeout);
> +
> + /* Entry is not ready for accessing. */
> + if (*data & DYNAMIC_MAC_TABLE_NOT_READY) {
> + return -EAGAIN;
> + /* Entry is ready for accessing. */
> + } else {
> + ksz_read8(dev, REG_IND_DATA_8, data);
> +
> + /* There is no valid entry in the table. */
> + if (*data & DYNAMIC_MAC_TABLE_MAC_EMPTY)
> + return -ENXIO;
> + }

You can drop else and one indentation level.

> + /* At least one valid entry in the table. */
> + } else {
> + u64 buf;
> + int cnt;
> +
> + ksz_get(dev, REG_IND_DATA_HI, &buf, sizeof(buf));
> + buf = be64_to_cpu(buf);

Would it make sense to convert endianness inside ksz_get?

Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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