From: Marc Kleine-Budde <mkl@pengutronix.de> To: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>, netdev@vger.kernel.org, wg@grandegger.com, linux-can@vger.kernel.org Cc: linux-sh@vger.kernel.org, vksavl@gmail.com Subject: Re: [PATCH v5] can: add Renesas R-Car CAN driver Date: Thu, 13 Feb 2014 12:12:53 +0000 [thread overview] Message-ID: <52FCB6C5.6020001@pengutronix.de> (raw) In-Reply-To: <52E3148E.2010608@cogentembedded.com> [-- Attachment #1: Type: text/plain, Size: 3825 bytes --] On 01/25/2014 02:34 AM, Sergei Shtylyov wrote: > Hello. > > On 01/20/2014 12:18 PM, Marc Kleine-Budde wrote: > >>> Add support for the CAN controller found in Renesas R-Car SoCs. > >>> Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> > >>> --- >>> The patch is against the 'linux-can-next.git' repo. > > [...] >>> Index: linux-can-next/drivers/net/can/rcar_can.c >>> =================================================================== >>> --- /dev/null >>> +++ linux-can-next/drivers/net/can/rcar_can.c >>> @@ -0,0 +1,857 @@ > [...] >>> +/* Mailbox registers structure */ >>> +struct rcar_can_mbox_regs { >>> + u32 id; /* IDE and RTR bits, SID and EID */ >>> + u8 stub; /* Not used */ >>> + u8 dlc; /* Data Length Code - bits [0..3] */ >>> + u8 data[8]; /* Data Bytes */ >>> + u8 tsh; /* Time Stamp Higher Byte */ >>> + u8 tsl; /* Time Stamp Lower Byte */ >>> +} __packed; > >> If you have contact to the hardware designer please blame him for > > Unfortunately, we don't. > >> placing the data register unaligned into the register space. :) > > It's not even the only one or worst example of questionable register > design in this module IMO. > > [...] >>> +static void rcar_can_tx_done(struct net_device *ndev) >>> +{ >>> + struct rcar_can_priv *priv = netdev_priv(ndev); >>> + struct net_device_stats *stats = &ndev->stats; >>> + int i; >>> + >>> + spin_lock(&priv->skb_lock); >>> + for (i = 0; i < priv->frames_queued; i++) >>> + can_get_echo_skb(ndev, i); >>> + stats->tx_bytes += priv->bytes_queued; >>> + stats->tx_packets += priv->frames_queued; >>> + priv->bytes_queued = 0; >>> + priv->frames_queued = 0; >>> + spin_unlock(&priv->skb_lock); > >> This looks broken. What happens if you send 2 CAN frames in a row, the >> first one is send, a TX complete interrupt is issued and you handle it >> here? You assume, that all CAN frames have been sent. > > TX interrupt will be issued only when TX FIFO gets empty (all 2 frames > have been transmitted in this case). Please see the comment to the > RCAR_CAN_MIER1_TXFIT bit. Does the hardware have a TX complete interrupt? If you only have TX FIFO empty, you have to limit the FIFO depth to 1. >>> +static irqreturn_t rcar_can_interrupt(int irq, void *dev_id) >>> +{ >>> + struct net_device *ndev = (struct net_device *)dev_id; > >> the cast is not needed > > Removed. > > [...] >>> +static void rcar_can_set_bittiming(struct net_device *dev) >>> +{ >>> + struct rcar_can_priv *priv = netdev_priv(dev); >>> + struct can_bittiming *bt = &priv->can.bittiming; >>> + u32 bcr; >>> + u8 clkr; >>> + >>> + /* Don't overwrite CLKR with 32-bit BCR access */ >>> + /* CLKR has 8-bit access */ > >> Can you explain the register layout here? Why do you access BCR with 32 >> bits when the register is defined as 3x8 bit? Can't you make it a >> standard 32 bit register? > > 1. According to documentation BCR is the 24-bit register. > Actually we can consider some 32-bit register that combines BCR and > CLKR but according to documentation there are two separate registers. > 2. BCR has 8- ,16-, and 32-bit access (according to documentation). > 3. This is the algorithm that the documentation suggests. > 4. We had a driver version with byte access but 32-bit access seems > shorter. Please use a normal read-modify-write 32 bit access. Marc -- Pengutronix e.K. | Marc Kleine-Budde | Industrial Linux Solutions | Phone: +49-231-2826-924 | Vertretung West/Dortmund | Fax: +49-5121-206917-5555 | Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de | [-- Attachment #2: OpenPGP digital signature --] [-- Type: application/pgp-signature, Size: 242 bytes --]
WARNING: multiple messages have this Message-ID (diff)
From: Marc Kleine-Budde <mkl@pengutronix.de> To: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>, netdev@vger.kernel.org, wg@grandegger.com, linux-can@vger.kernel.org Cc: linux-sh@vger.kernel.org, vksavl@gmail.com Subject: Re: [PATCH v5] can: add Renesas R-Car CAN driver Date: Thu, 13 Feb 2014 13:12:53 +0100 [thread overview] Message-ID: <52FCB6C5.6020001@pengutronix.de> (raw) In-Reply-To: <52E3148E.2010608@cogentembedded.com> [-- Attachment #1: Type: text/plain, Size: 3825 bytes --] On 01/25/2014 02:34 AM, Sergei Shtylyov wrote: > Hello. > > On 01/20/2014 12:18 PM, Marc Kleine-Budde wrote: > >>> Add support for the CAN controller found in Renesas R-Car SoCs. > >>> Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> > >>> --- >>> The patch is against the 'linux-can-next.git' repo. > > [...] >>> Index: linux-can-next/drivers/net/can/rcar_can.c >>> =================================================================== >>> --- /dev/null >>> +++ linux-can-next/drivers/net/can/rcar_can.c >>> @@ -0,0 +1,857 @@ > [...] >>> +/* Mailbox registers structure */ >>> +struct rcar_can_mbox_regs { >>> + u32 id; /* IDE and RTR bits, SID and EID */ >>> + u8 stub; /* Not used */ >>> + u8 dlc; /* Data Length Code - bits [0..3] */ >>> + u8 data[8]; /* Data Bytes */ >>> + u8 tsh; /* Time Stamp Higher Byte */ >>> + u8 tsl; /* Time Stamp Lower Byte */ >>> +} __packed; > >> If you have contact to the hardware designer please blame him for > > Unfortunately, we don't. > >> placing the data register unaligned into the register space. :) > > It's not even the only one or worst example of questionable register > design in this module IMO. > > [...] >>> +static void rcar_can_tx_done(struct net_device *ndev) >>> +{ >>> + struct rcar_can_priv *priv = netdev_priv(ndev); >>> + struct net_device_stats *stats = &ndev->stats; >>> + int i; >>> + >>> + spin_lock(&priv->skb_lock); >>> + for (i = 0; i < priv->frames_queued; i++) >>> + can_get_echo_skb(ndev, i); >>> + stats->tx_bytes += priv->bytes_queued; >>> + stats->tx_packets += priv->frames_queued; >>> + priv->bytes_queued = 0; >>> + priv->frames_queued = 0; >>> + spin_unlock(&priv->skb_lock); > >> This looks broken. What happens if you send 2 CAN frames in a row, the >> first one is send, a TX complete interrupt is issued and you handle it >> here? You assume, that all CAN frames have been sent. > > TX interrupt will be issued only when TX FIFO gets empty (all 2 frames > have been transmitted in this case). Please see the comment to the > RCAR_CAN_MIER1_TXFIT bit. Does the hardware have a TX complete interrupt? If you only have TX FIFO empty, you have to limit the FIFO depth to 1. >>> +static irqreturn_t rcar_can_interrupt(int irq, void *dev_id) >>> +{ >>> + struct net_device *ndev = (struct net_device *)dev_id; > >> the cast is not needed > > Removed. > > [...] >>> +static void rcar_can_set_bittiming(struct net_device *dev) >>> +{ >>> + struct rcar_can_priv *priv = netdev_priv(dev); >>> + struct can_bittiming *bt = &priv->can.bittiming; >>> + u32 bcr; >>> + u8 clkr; >>> + >>> + /* Don't overwrite CLKR with 32-bit BCR access */ >>> + /* CLKR has 8-bit access */ > >> Can you explain the register layout here? Why do you access BCR with 32 >> bits when the register is defined as 3x8 bit? Can't you make it a >> standard 32 bit register? > > 1. According to documentation BCR is the 24-bit register. > Actually we can consider some 32-bit register that combines BCR and > CLKR but according to documentation there are two separate registers. > 2. BCR has 8- ,16-, and 32-bit access (according to documentation). > 3. This is the algorithm that the documentation suggests. > 4. We had a driver version with byte access but 32-bit access seems > shorter. Please use a normal read-modify-write 32 bit access. Marc -- Pengutronix e.K. | Marc Kleine-Budde | Industrial Linux Solutions | Phone: +49-231-2826-924 | Vertretung West/Dortmund | Fax: +49-5121-206917-5555 | Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de | [-- Attachment #2: OpenPGP digital signature --] [-- Type: application/pgp-signature, Size: 242 bytes --]
next prev parent reply other threads:[~2014-02-13 12:12 UTC|newest] Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top 2013-12-26 20:37 [PATCH v5] can: add Renesas R-Car CAN driver Sergei Shtylyov 2013-12-26 21:37 ` Sergei Shtylyov 2014-01-13 13:46 ` Sergei Shtylyov 2014-01-13 13:46 ` Sergei Shtylyov 2014-01-20 9:18 ` Marc Kleine-Budde 2014-01-20 9:18 ` Marc Kleine-Budde 2014-01-25 0:34 ` Sergei Shtylyov 2014-01-25 1:34 ` Sergei Shtylyov 2014-02-13 12:12 ` Marc Kleine-Budde [this message] 2014-02-13 12:12 ` Marc Kleine-Budde 2014-02-20 22:48 ` Sergei Shtylyov 2014-02-20 23:48 ` Sergei Shtylyov 2014-02-28 9:08 ` Marc Kleine-Budde 2014-02-28 9:08 ` Marc Kleine-Budde 2014-02-28 11:16 ` Sergei Shtylyov 2014-02-28 11:16 ` Sergei Shtylyov 2014-02-28 11:37 ` Marc Kleine-Budde 2014-02-28 11:37 ` Marc Kleine-Budde 2014-02-28 11:41 ` Geert Uytterhoeven 2014-02-28 11:41 ` Geert Uytterhoeven 2014-02-28 11:47 ` David Laight 2014-02-28 11:47 ` David Laight 2014-02-28 11:50 ` Marc Kleine-Budde 2014-02-28 11:50 ` Marc Kleine-Budde 2014-02-28 12:02 ` David Laight 2014-02-28 12:02 ` David Laight 2014-02-28 11:49 ` Marc Kleine-Budde 2014-02-28 11:49 ` Marc Kleine-Budde 2014-02-28 12:05 ` Sergei Shtylyov 2014-02-28 12:05 ` Sergei Shtylyov 2014-02-28 12:17 ` David Laight 2014-02-28 12:17 ` David Laight 2014-02-28 12:34 ` Sergei Shtylyov 2014-02-28 12:34 ` Sergei Shtylyov 2014-01-20 11:43 ` Geert Uytterhoeven 2014-01-20 11:43 ` Geert Uytterhoeven 2014-01-20 11:47 ` Marc Kleine-Budde 2014-01-20 11:47 ` Marc Kleine-Budde 2014-01-20 11:52 ` Geert Uytterhoeven 2014-01-20 11:52 ` Geert Uytterhoeven 2014-01-20 11:58 ` Marc Kleine-Budde 2014-01-20 11:58 ` Marc Kleine-Budde 2014-01-20 12:02 ` Ben Dooks 2014-01-20 12:05 ` Geert Uytterhoeven 2014-01-20 12:05 ` Geert Uytterhoeven 2014-01-20 12:08 ` Marc Kleine-Budde 2014-01-20 12:08 ` Marc Kleine-Budde 2014-01-20 12:05 ` Marc Kleine-Budde 2014-01-20 12:05 ` Marc Kleine-Budde 2014-01-20 12:13 ` David Laight 2014-01-20 12:13 ` David Laight 2014-01-20 12:35 ` Marc Kleine-Budde 2014-01-20 12:35 ` Marc Kleine-Budde 2014-01-20 19:16 ` David Miller 2014-01-20 19:16 ` David Miller 2014-01-20 21:12 ` Sergei Shtylyov 2014-01-20 22:12 ` Sergei Shtylyov 2014-01-20 21:17 ` Marc Kleine-Budde 2014-01-20 21:17 ` Marc Kleine-Budde 2014-01-22 11:52 ` Ben Dooks 2014-01-22 11:54 ` Geert Uytterhoeven 2014-01-22 11:54 ` Geert Uytterhoeven 2014-01-22 11:58 ` David Laight 2014-01-22 11:58 ` David Laight 2014-01-20 12:12 ` Sergei Shtylyov 2014-01-20 12:12 ` Sergei Shtylyov
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=52FCB6C5.6020001@pengutronix.de \ --to=mkl@pengutronix.de \ --cc=linux-can@vger.kernel.org \ --cc=linux-sh@vger.kernel.org \ --cc=netdev@vger.kernel.org \ --cc=sergei.shtylyov@cogentembedded.com \ --cc=vksavl@gmail.com \ --cc=wg@grandegger.com \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.