From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: Andrew Lunn <andrew@lunn.ch>
Cc: "Pali Rohár" <pali@kernel.org>,
"David S. Miller" <davem@davemloft.net>,
"Jakub Kicinski" <kuba@kernel.org>,
"Thomas Schreiber" <tschreibe@gmail.com>,
"Heiner Kallweit" <hkallweit1@gmail.com>,
"Marek Behún" <kabel@kernel.org>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/3] net: sfp: add workaround for Realtek RTL8672 and RTL9601C chips
Date: Thu, 7 Jan 2021 19:45:49 +0000 [thread overview]
Message-ID: <20210107194549.GR1551@shell.armlinux.org.uk> (raw)
In-Reply-To: <X/dCm1fK9jcjs4XT@lunn.ch>
On Thu, Jan 07, 2021 at 06:19:23PM +0100, Andrew Lunn wrote:
> > -static int sfp_quirk_i2c_block_size(const struct sfp_eeprom_base *base)
> > +static bool sfp_id_needs_byte_io(struct sfp *sfp, void *buf, size_t len)
> > {
> > - if (!memcmp(base->vendor_name, "VSOL ", 16))
> > - return 1;
> > - if (!memcmp(base->vendor_name, "OEM ", 16) &&
> > - !memcmp(base->vendor_pn, "V2801F ", 16))
> > - return 1;
> > + size_t i, block_size = sfp->i2c_block_size;
> >
> > - /* Some modules can't cope with long reads */
> > - return 16;
> > -}
> > + /* Already using byte IO */
> > + if (block_size == 1)
> > + return false;
>
> This seems counter intuitive. We don't need byte IO because we are
> doing btye IO? Can we return True here?
It is counter-intuitive, but as this is indicating whether we need to
switch to byte IO, if we're already doing byte IO, then we don't need
to switch.
> > -static void sfp_quirks_base(struct sfp *sfp, const struct sfp_eeprom_base *base)
> > -{
> > - sfp->i2c_block_size = sfp_quirk_i2c_block_size(base);
> > + for (i = 1; i < len; i += block_size) {
> > + if (memchr_inv(buf + i, '\0', block_size - 1))
> > + return false;
> > + }
>
> Is the loop needed?
I think you're not reading the code very well. It checks for bytes at
offset 1..blocksize-1, blocksize+1..2*blocksize-1, etc are zero. It
does _not_ check that byte 0 or the byte at N*blocksize is zero - these
bytes are skipped. In other words, the first byte of each transfer can
be any value. The other bytes of the _entire_ ID must be zero.
> I also wonder if on the last iteration of the loop you go passed the
> end of buf? Don't you need a min(block_size -1, len - i) or
> similar?
The ID is 64 bytes long, and is fixed. block_size could be a non-power
of two, but that is highly unlikely. block_size will never be larger
than 16 either.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
next prev parent reply other threads:[~2021-01-07 19:47 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-30 15:47 [PATCH 0/4] net: sfp: add support for GPON RTL8672/RTL9601C and Ubiquiti U-Fiber Pali Rohár
2020-12-30 15:47 ` [PATCH 1/4] net: sfp: add workaround for Realtek RTL8672 and RTL9601C chips Pali Rohár
2020-12-30 16:10 ` Russell King - ARM Linux admin
2020-12-30 16:56 ` Pali Rohár
2020-12-30 17:05 ` Russell King - ARM Linux admin
2020-12-30 17:13 ` Andrew Lunn
2020-12-30 17:43 ` Pali Rohár
2020-12-30 19:09 ` Russell King - ARM Linux admin
2020-12-30 19:49 ` Andrew Lunn
2020-12-31 12:14 ` Pali Rohár
2020-12-31 15:09 ` Andrew Lunn
2020-12-31 15:40 ` Pali Rohár
2020-12-31 15:30 ` Andrew Lunn
2020-12-31 17:00 ` Pali Rohár
2020-12-31 17:13 ` Andrew Lunn
2021-01-02 1:49 ` Pali Rohár
2021-01-03 2:25 ` Thomas Schreiber
2021-01-03 2:41 ` Pali Rohár
2021-01-06 14:55 ` Pali Rohár
2021-01-06 15:21 ` Russell King - ARM Linux admin
2021-01-06 15:23 ` Russell King - ARM Linux admin
2021-01-06 15:27 ` Russell King - ARM Linux admin
2021-01-06 15:35 ` Pali Rohár
2020-12-30 19:30 ` Andrew Lunn
2020-12-30 19:39 ` Russell King - ARM Linux admin
2020-12-30 17:31 ` Pali Rohár
2020-12-30 19:18 ` Russell King - ARM Linux admin
2020-12-30 15:47 ` [PATCH 2/4] net: sfp: allow to use also SFP modules which are detected as SFF Pali Rohár
2020-12-30 16:11 ` Russell King - ARM Linux admin
2020-12-30 17:06 ` Pali Rohár
2020-12-30 17:27 ` Marek Behún
2020-12-30 19:12 ` Russell King - ARM Linux admin
2020-12-31 13:52 ` Pali Rohár
2020-12-30 15:47 ` [PATCH 3/4] net: sfp: assume that LOS is not implemented if both LOS normal and inverted is set Pali Rohár
2020-12-30 16:13 ` Russell King - ARM Linux admin
2020-12-30 16:57 ` Pali Rohár
2020-12-30 17:06 ` Russell King - ARM Linux admin
2020-12-30 17:17 ` Andrew Lunn
2020-12-30 17:32 ` Pali Rohár
2020-12-30 15:47 ` [PATCH 4/4] net: sfp: add mode quirk for GPON module Ubiquiti U-Fiber Instant Pali Rohár
2021-01-06 15:37 ` [PATCH v2 0/3] net: sfp: add support for GPON RTL8672/RTL9601C and Ubiquiti U-Fiber Pali Rohár
2021-01-06 15:37 ` [PATCH v2 1/3] net: sfp: add workaround for Realtek RTL8672 and RTL9601C chips Pali Rohár
2021-01-07 2:02 ` Andrew Lunn
2021-01-07 9:08 ` Pali Rohár
2021-01-07 17:19 ` Andrew Lunn
2021-01-07 17:40 ` Russell King - ARM Linux admin
2021-01-07 19:18 ` Pali Rohár
2021-01-07 19:17 ` Pali Rohár
2021-01-07 19:45 ` Russell King - ARM Linux admin [this message]
2021-01-07 20:21 ` Marek Behún
2021-01-08 0:49 ` Pali Rohár
2021-01-06 15:37 ` [PATCH v2 2/3] net: sfp: assume that LOS is not implemented if both LOS normal and inverted is set Pali Rohár
2021-01-07 16:54 ` Andrew Lunn
2021-01-09 15:46 ` Russell King - ARM Linux admin
2021-01-09 15:54 ` Andrew Lunn
2021-01-09 16:27 ` Russell King - ARM Linux admin
2021-01-09 19:14 ` Pali Rohár
2021-01-09 23:19 ` Russell King - ARM Linux admin
2021-01-09 23:50 ` Pali Rohár
2021-01-06 15:37 ` [PATCH v2 3/3] net: sfp: add mode quirk for GPON module Ubiquiti U-Fiber Instant Pali Rohár
2021-01-07 16:51 ` Andrew Lunn
2021-01-11 11:39 ` [PATCH v3 0/2] net: sfp: add support for GPON RTL8672/RTL9601C and Ubiquiti U-Fiber Pali Rohár
2021-01-11 11:39 ` [PATCH v3 1/2] net: sfp: add workaround for Realtek RTL8672 and RTL9601C chips Pali Rohár
2021-01-11 15:28 ` Marek Behún
2021-01-11 11:39 ` [PATCH v3 2/2] net: sfp: add mode quirk for GPON module Ubiquiti U-Fiber Instant Pali Rohár
2021-01-11 15:32 ` Marek Behún
2021-01-12 13:33 ` [PATCH v3 0/2] net: sfp: add support for GPON RTL8672/RTL9601C and Ubiquiti U-Fiber Pali Rohár
2021-01-18 9:34 ` Pali Rohár
2021-01-25 14:09 ` Pali Rohár
2021-01-25 14:16 ` Russell King - ARM Linux admin
2021-01-25 14:23 ` Pali Rohár
2021-01-25 14:42 ` Russell King - ARM Linux admin
2021-01-25 14:47 ` Pali Rohár
2021-01-25 15:41 ` Andrew Lunn
2021-01-25 15:02 ` [PATCH v4 " Pali Rohár
2021-01-25 15:02 ` [PATCH v4 1/2] net: sfp: add workaround for Realtek RTL8672 and RTL9601C chips Pali Rohár
2021-01-25 15:02 ` [PATCH v4 2/2] net: sfp: add mode quirk for GPON module Ubiquiti U-Fiber Instant Pali Rohár
2021-01-28 21:50 ` [PATCH v4 0/2] net: sfp: add support for GPON RTL8672/RTL9601C and Ubiquiti U-Fiber patchwork-bot+netdevbpf
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