Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
To:     Jeroen Hofstee <jhofstee@victronenergy.com>,
        "linux-can@vger.kernel.org" <linux-can@vger.kernel.org>
Cc:     Anant Gole <anantgole@ti.com>, AnilKumar Ch <anilkumar@ti.com>,
        Wolfgang Grandegger <wg@grandegger.com>,
        "David S. Miller" <davem@davemloft.net>,
        "open list:NETWORKING DRIVERS" <netdev@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>
References: <1556539376-20932-1-git-send-email-jhofstee@victronenergy.com>
From:   Marc Kleine-Budde <mkl@pengutronix.de>
Openpgp: preference=signencrypt
Autocrypt: addr=mkl@pengutronix.de; prefer-encrypt=mutual; keydata=
 mQINBFFVq30BEACtnSvtXHoeHJxG6nRULcvlkW6RuNwHKmrqoksispp43X8+nwqIFYgb8UaX
 zu8T6kZP2wEIpM9RjEL3jdBjZNCsjSS6x1qzpc2+2ivjdiJsqeaagIgvy2JWy7vUa4/PyGfx
 QyUeXOxdj59DvLwAx8I6hOgeHx2X/ntKAMUxwawYfPZpP3gwTNKc27dJWSomOLgp+gbmOmgc
 6U5KwhAxPTEb3CsT5RicsC+uQQFumdl5I6XS+pbeXZndXwnj5t84M+HEj7RN6bUfV2WZO/AB
 Xt5+qFkC/AVUcj/dcHvZwQJlGeZxoi4veCoOT2MYqfR0ax1MmN+LVRvKm29oSyD4Ts/97cbs
 XsZDRxnEG3z/7Winiv0ZanclA7v7CQwrzsbpCv+oj+zokGuKasofzKdpywkjAfSE1zTyF+8K
 nxBAmzwEqeQ3iKqBc3AcCseqSPX53mPqmwvNVS2GqBpnOfY7Mxr1AEmxdEcRYbhG6Xdn+ACq
 Dq0Db3A++3PhMSaOu125uIAIwMXRJIzCXYSqXo8NIeo9tobk0C/9w3fUfMTrBDtSviLHqlp8
 eQEP8+TDSmRP/CwmFHv36jd+XGmBHzW5I7qw0OORRwNFYBeEuiOIgxAfjjbLGHh9SRwEqXAL
 kw+WVTwh0MN1k7I9/CDVlGvc3yIKS0sA+wudYiselXzgLuP5cQARAQABtCZNYXJjIEtsZWlu
 ZS1CdWRkZSA8bWtsQHBlbmd1dHJvbml4LmRlPokCVAQTAQoAPgIbAwIeAQIXgAULCQgHAwUV
 CgkICwUWAgMBABYhBMFAC6CzmJ5vvH1bXCte4hHFiupUBQJcUsSbBQkM366zAAoJECte4hHF
 iupUgkAP/2RdxKPZ3GMqag33jKwKAbn/fRqAFWqUH9TCsRH3h6+/uEPnZdzhkL4a9p/6OeJn
 Z6NXqgsyRAOTZsSFcwlfxLNHVxBWm8pMwrBecdt4lzrjSt/3ws2GqxPsmza1Gs61lEdYvLST
 Ix2vPbB4FAfE0kizKAjRZzlwOyuHOr2ilujDsKTpFtd8lV1nBNNn6HBIBR5ShvJnwyUdzuby
 tOsSt7qJEvF1x3y49bHCy3uy+MmYuoEyG6zo9udUzhVsKe3hHYC2kfB16ZOBjFC3lH2U5An+
 yQYIIPZrSWXUeKjeMaKGvbg6W9Oi4XEtrwpzUGhbewxCZZCIrzAH2hz0dUhacxB201Y/faY6
 BdTS75SPs+zjTYo8yE9Y9eG7x/lB60nQjJiZVNvZ88QDfVuLl/heuIq+fyNajBbqbtBT5CWf
 mOP4Dh4xjm3Vwlz8imWW/drEVJZJrPYqv0HdPbY8jVMpqoe5jDloyVn3prfLdXSbKPexlJaW
 5tnPd4lj8rqOFShRnLFCibpeHWIumqrIqIkiRA9kFW3XMgtU6JkIrQzhJb6Tc6mZg2wuYW0d
 Wo2qvdziMgPkMFiWJpsxM9xPk9BBVwR+uojNq5LzdCsXQ2seG0dhaOTaaIDWVS8U/V8Nqjrl
 6bGG2quo5YzJuXKjtKjZ4R6k762pHJ3tnzI/jnlc1sXzuQENBFxSzJYBCAC58uHRFEjVVE3J
 31eyEQT6H1zSFCccTMPO/ewwAnotQWo98Bc67ecmprcnjRjSUKTbyY/eFxS21JnC4ZB0pJKx
 MNwK6zq71wLmpseXOgjufuG3kvCgwHLGf/nkBHXmSINHvW00eFK/kJBakwHEbddq8Dr4ewmr
 G7yr8d6A3CSn/qhOYWhIxNORK3SVo4Io7ExNX/ljbisGsgRzsWvY1JlN4sabSNEr7a8YaqTd
 2CfFe/5fPcQRGsfhAbH2pVGigr7JddONJPXGE7XzOrx5KTwEv19H6xNe+D/W3FwjZdO4TKIo
 vcZveSDrFWOi4o2Te4O5OB/2zZbNWPEON8MaXi9zABEBAAGJA3IEGAEKACYWIQTBQAugs5ie
 b7x9W1wrXuIRxYrqVAUCXFLMlgIbAgUJAeKNmgFACRArXuIRxYrqVMB0IAQZAQoAHRYhBJrx
 JF84Dn3PPNRrhVrGIaOR5J0gBQJcUsyWAAoJEFrGIaOR5J0grw4H/itil/yryJCvzi6iuZHS
 suSHHOiEf+UQHib1MLP96LM7FmDabjVSmJDpH4TsMu17A0HTG+bPMAdeia0+q9FWSvSHYW8D
 wNhfkb8zojpa37qBpVpiNy7r6BKGSRSoFOv6m/iIoRJuJ041AEKao6djj/FdQF8OV1EtWKRO
 +nE2bNuDCcwHkhHP+FHExdzhKSmnIsMjGpGwIQKN6DxlJ7fN4W7UZFIQdSO21ei+akinBo4K
 O0uNCnVmePU1UzrwXKG2sS2f97A+sZE89vkc59NtfPHhofI3JkmYexIF6uqLA3PumTqLQ2Lu
 bywPAC3YNphlhmBrG589p+sdtwDQlpoH9O7NeBAAg/lyGOUUIONrheii/l/zR0xxr2TDE6tq
 6HZWdtjWoqcaky6MSyJQIeJ20AjzdV/PxMkd8zOijRVTnlK44bcfidqFM6yuT1bvXAO6NOPy
 pvBRnfP66L/xECnZe7s07rXpNFy72XGNZwhj89xfpK4a9E8HQcOD0mNtCJaz7TTugqBOsQx2
 45VPHosmhdtBQ6/gjlf2WY9FXb5RyceeSuK4lVrz9uZB+fUHBge/giOSsrqFo/9fWAZsE67k
 6Mkdbpc7ZQwxelcpP/giB9N+XAfBsffQ8q6kIyuFV4ILsIECCIA4nt1rYmzphv6t5J6PmlTq
 TzW9jNzbYANoOFAGnjzNRyc9i8UiLvjhTzaKPBOkQfhStEJaZrdSWuR/7Tt2wZBBoNTsgNAw
 A+cEu+SWCvdX7vNpsCHMiHtcEmVt5R0Tex1Ky87EfXdnGR2mDi6Iyxi3MQcHez3C61Ga3Baf
 P8UtXR6zrrrlX22xXtpNJf4I4Z6RaLpB/avIXTFXPbJ8CUUbVD2R2mZ/jyzaTzgiABDZspbS
 gw17QQUrKqUog0nHXuaGGA1uvreHTnyBWx5P8FP7rhtvYKhw6XdJ06ns+2SFcQv0Bv6PcSDK
 aRXmnW+OsDthn84x1YkfGIRJEPvvmiOKQsFEiB4OUtTX2pheYmZcZc81KFfJMmE8Z9+LT6Ry
 uSS5AQ0EXFLNDgEIAL14qAzTMCE1PwRrYJRI/RSQGAGF3HLdYvjbQd9Ozzg02K3mNCF2Phb1
 cjsbMk/V6WMxYoZCEtCh4X2GjQG2GDDW4KC9HOa8cTmr9Vcno+f+pUle09TMzWDgtnH92WKx
 d0FIQev1zDbxU7lk1dIqyOjjpyhmR8Put6vgunvuIjGJ/GapHL/O0yjVlpumtmow6eME2muc
 TeJjpapPWBGcy/8VU4LM8xMeMWv8DtQML5ogyJxZ0Smt+AntIzcF9miV2SeYXA3OFiojQstF
 vScN7owL1XiQ3UjJotCp6pUcSVgVv0SgJXbDo5Nv87M2itn68VPfTu2uBBxRYqXQovsR++kA
 EQEAAYkCPAQYAQoAJhYhBMFAC6CzmJ5vvH1bXCte4hHFiupUBQJcUs0OAhsMBQkB4o0iAAoJ
 ECte4hHFiupUbioQAJ40bEJmMOF28vFcGvQrpI+lfHJGk9zSrh4F4SlJyOVWV1yWyUAINr8w
 v1aamg2nAppZ16z4nAnGU/47tWZ4P8blLVG8x4SWzz3D7MCy1FsQBTrWGLqWldPhkBAGp2VH
 xDOK4rLhuQWx3H5zd3kPXaIgvHI3EliWaQN+u2xmTQSJN75I/V47QsaPvkm4TVe3JlB7l1Fg
 OmSvYx31YC+3slh89ayjPWt8hFaTLnB9NaW9bLhs3E2ESF9Dei0FRXIt3qnFV/hnETsx3X4h
 KEnXxhSRDVeURP7V6P/z3+WIfddVKZk5ZLHi39fJpxvsg9YLSfStMJ/cJfiPXk1vKdoa+FjN
 7nGAZyF6NHTNhsI7aHnvZMDavmAD3lK6CY+UBGtGQA3QhrUc2cedp1V53lXwor/D/D3Wo9wY
 iSXKOl4fFCh2Peo7qYmFUaDdyiCxvFm+YcIeMZ8wO5udzkjDtP4lWKAn4tUcdcwMOT5d0I3q
 WATP4wFI8QktNBqF3VY47HFwF9PtNuOZIqeAquKezywUc5KqKdqEWCPx9pfLxBAh3GW2Zfjp
 lP6A5upKs2ktDZOC2HZXP4IJ1GTk8hnfS4ade8s9FNcwu9m3JlxcGKLPq5DnIbPVQI1UUR4F
 QyAqTtIdSpeFYbvH8D7pO4lxLSz2ZyBMk+aKKs6GL5MqEci8OcFW
Subject: Re: [PATCH] can: ti_hecc: use timestamp based rx-offloading
Message-ID: <5881cb80-883b-a96b-2939-973150cfc196@pengutronix.de>
Date:   Wed, 24 Jul 2019 10:26:02 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101
 Thunderbird/60.8.0
MIME-Version: 1.0
In-Reply-To: <1556539376-20932-1-git-send-email-jhofstee@victronenergy.com>
Content-Type: multipart/signed; micalg=pgp-sha512;
 protocol="application/pgp-signature";
 boundary="0TGN2duKhCYiG04TA8avalkRqpNrVCmIu"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

This is an OpenPGP/MIME signed message (RFC 4880 and 3156)
--0TGN2duKhCYiG04TA8avalkRqpNrVCmIu
Content-Type: multipart/mixed; boundary="wOe0gYcUEepxQHwDfsJDd7ZqTtKeTJmc8";
 protected-headers="v1"
From: Marc Kleine-Budde <mkl@pengutronix.de>
To: Jeroen Hofstee <jhofstee@victronenergy.com>,
 "linux-can@vger.kernel.org" <linux-can@vger.kernel.org>
Cc: Anant Gole <anantgole@ti.com>, AnilKumar Ch <anilkumar@ti.com>,
 Wolfgang Grandegger <wg@grandegger.com>,
 "David S. Miller" <davem@davemloft.net>,
 "open list:NETWORKING DRIVERS" <netdev@vger.kernel.org>,
 open list <linux-kernel@vger.kernel.org>
Message-ID: <5881cb80-883b-a96b-2939-973150cfc196@pengutronix.de>
Subject: Re: [PATCH] can: ti_hecc: use timestamp based rx-offloading
References: <1556539376-20932-1-git-send-email-jhofstee@victronenergy.com>
In-Reply-To: <1556539376-20932-1-git-send-email-jhofstee@victronenergy.com>

--wOe0gYcUEepxQHwDfsJDd7ZqTtKeTJmc8
Content-Type: text/plain; charset=utf-8
Content-Language: de-DE
Content-Transfer-Encoding: quoted-printable

On 4/29/19 2:03 PM, Jeroen Hofstee wrote:
> As already mentioned in [1] and included in [2], there is an off by one=

> issue since the high bank is already enabled when the _next_ mailbox to=

> be read has index 12, so the mailbox being read was 13. The message can=

> therefore go into mailbox 31 and the driver will be repolled until the
> mailbox 12 eventually receives a msg. Or the message might end up in th=
e
> 12th mailbox, but then it would become disabled after reading it and on=
ly
> be enabled again in the next "round" after mailbox 13 was read, which c=
an
> cause out of order messages, since the lower priority mailboxes can
> accept messages in the meantime.
>=20
> As mentioned in [3] there is a hardware race condition when changing th=
e
> CANME register while messages are being received. Even when including a=

> busy poll on reception, like in [2] there are still overflows and out o=
f
> order messages at times, but less then without the busy loop polling.
> Unlike what the patch suggests, the polling time is not in the microsec=
ond
> range, but takes as long as a current CAN bus reception needs to finish=
,
> so typically more in the fraction of millisecond range. Since the timeo=
ut
> is in jiffies it won't timeout.
>=20
> Even with these additional fixes the driver is still not able to provid=
e a
> proper FIFO which doesn't drop packages. So change the driver to use
> rx-offload and base order on timestamp instead of message box numbers. =
As
> a side affect, this also fixes [4] and [5].
>=20
> Before this change messages with a single byte counter were dropped /
> received out of order at a bitrate of 250kbit/s on an am3517. With this=

> patch that no longer occurs up to and including 1Mbit/s.
>=20
> [1] https://linux-can.vger.kernel.narkive.com/zgO9inVi/patch-can-ti-hec=
c-fix-rx-wrong-sequence-issue#post6
> [2] http://arago-project.org/git/projects/?p=3Dlinux-omap3.git;a=3Dcomm=
it;h=3D02346892777f07245de4d5af692513ebd852dcb2
> [3] https://linux-can.vger.kernel.narkive.com/zgO9inVi/patch-can-ti-hec=
c-fix-rx-wrong-sequence-issue#post5
> [4] https://patchwork.ozlabs.org/patch/895956/
> [5] https://www.spinics.net/lists/netdev/msg494971.html
>=20
> Cc: Anant Gole <anantgole@ti.com>
> Cc: AnilKumar Ch <anilkumar@ti.com>
> Signed-off-by: Jeroen Hofstee <jhofstee@victronenergy.com>
> ---
>  drivers/net/can/ti_hecc.c | 189 +++++++++++++-------------------------=
--------
>  1 file changed, 53 insertions(+), 136 deletions(-)
>=20
> diff --git a/drivers/net/can/ti_hecc.c b/drivers/net/can/ti_hecc.c
> index db6ea93..fe7ffff 100644
> --- a/drivers/net/can/ti_hecc.c
> +++ b/drivers/net/can/ti_hecc.c
> @@ -5,6 +5,7 @@
>   * specs for the same is available at <http://www.ti.com>
>   *
>   * Copyright (C) 2009 Texas Instruments Incorporated - http://www.ti.c=
om/
> + * Copyright (C) 2019 Jeroen Hofstee <jhofstee@victronenergy.com>
>   *
>   * This program is free software; you can redistribute it and/or
>   * modify it under the terms of the GNU General Public License as
> @@ -34,6 +35,7 @@
>  #include <linux/can/dev.h>
>  #include <linux/can/error.h>
>  #include <linux/can/led.h>
> +#include <linux/can/rx-offload.h>
> =20
>  #define DRV_NAME "ti_hecc"
>  #define HECC_MODULE_VERSION     "0.7"
> @@ -63,29 +65,16 @@ MODULE_VERSION(HECC_MODULE_VERSION);
>  #define HECC_TX_PRIO_MASK	(MAX_TX_PRIO << HECC_MB_TX_SHIFT)
>  #define HECC_TX_MB_MASK		(HECC_MAX_TX_MBOX - 1)
>  #define HECC_TX_MASK		((HECC_MAX_TX_MBOX - 1) | HECC_TX_PRIO_MASK)
> -#define HECC_TX_MBOX_MASK	(~(BIT(HECC_MAX_TX_MBOX) - 1))
> -#define HECC_DEF_NAPI_WEIGHT	HECC_MAX_RX_MBOX
> =20
>  /*
> - * Important Note: RX mailbox configuration
> - * RX mailboxes are further logically split into two - main and buffer=

> - * mailboxes. The goal is to get all packets into main mailboxes as
> - * driven by mailbox number and receive priority (higher to lower) and=

> - * buffer mailboxes are used to receive pkts while main mailboxes are =
being
> - * processed. This ensures in-order packet reception.
> - *
> - * Here are the recommended values for buffer mailbox. Note that RX ma=
ilboxes
> - * start after TX mailboxes:
> - *
> - * HECC_MAX_RX_MBOX		HECC_RX_BUFFER_MBOX	No of buffer mailboxes
> - * 28				12			8
> - * 16				20			4
> + * RX mailbox configuration
> + * The remaining mailboxes are used for reception and are delivered ba=
sed on
> + * their timestamp, to avoid a hardware race when CANME is changed whi=
le
> + * CAN-bus traffix is being received.
>   */
> =20
>  #define HECC_MAX_RX_MBOX	(HECC_MAX_MAILBOXES - HECC_MAX_TX_MBOX)
> -#define HECC_RX_BUFFER_MBOX	12 /* as per table above */
>  #define HECC_RX_FIRST_MBOX	(HECC_MAX_MAILBOXES - 1)
> -#define HECC_RX_HIGH_MBOX_MASK	(~(BIT(HECC_RX_BUFFER_MBOX) - 1))
> =20
>  /* TI HECC module registers */
>  #define HECC_CANME		0x0	/* Mailbox enable */
> @@ -123,6 +112,8 @@ MODULE_VERSION(HECC_MODULE_VERSION);
>  #define HECC_CANMDL		0x8
>  #define HECC_CANMDH		0xC
> =20
> +#define HECC_CANMOTS		0x100

It's actually 0x80

> +
>  #define HECC_SET_REG		0xFFFFFFFF
>  #define HECC_CANID_MASK		0x3FF	/* 18 bits mask for extended id's */
>  #define HECC_CCE_WAIT_COUNT     100	/* Wait for ~1 sec for CCE bit */
> @@ -193,7 +184,7 @@ static const struct can_bittiming_const ti_hecc_bit=
timing_const =3D {
> =20
>  struct ti_hecc_priv {
>  	struct can_priv can;	/* MUST be first member/field */
> -	struct napi_struct napi;
> +	struct can_rx_offload offload;
>  	struct net_device *ndev;
>  	struct clk *clk;
>  	void __iomem *base;
> @@ -203,7 +194,6 @@ struct ti_hecc_priv {
>  	spinlock_t mbx_lock; /* CANME register needs protection */
>  	u32 tx_head;
>  	u32 tx_tail;
> -	u32 rx_next;
>  	struct regulator *reg_xceiver;
>  };
> =20
> @@ -265,6 +255,11 @@ static inline u32 hecc_get_bit(struct ti_hecc_priv=
 *priv, int reg, u32 bit_mask)
>  	return (hecc_read(priv, reg) & bit_mask) ? 1 : 0;
>  }
> =20
> +static inline u32 hecc_read_stamp(struct ti_hecc_priv *priv, u32 mbxno=
)
> +{
> +	return __raw_readl(priv->hecc_ram + 0x80 + 4 * mbxno);

I've changed this function to use HECC_CANMOTS.

Marc

--=20
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   |


--wOe0gYcUEepxQHwDfsJDd7ZqTtKeTJmc8--

--0TGN2duKhCYiG04TA8avalkRqpNrVCmIu
Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: OpenPGP digital signature
Content-Disposition: attachment; filename="signature.asc"

-----BEGIN PGP SIGNATURE-----

iQEzBAEBCgAdFiEEmvEkXzgOfc881GuFWsYho5HknSAFAl04FhoACgkQWsYho5Hk
nSDbcAgAowGB7FaxEXpOn0rkFgKcX+WreYg4QLIoqkXsUAZOPLSXCh40RxrwBrNj
pNQw2F/hgSwn+0raPQrbfDjufSJ37KevDZlrDZJ7+yHx7Qnm485C+QArCyIBFg+d
xbAwHX2hagaRS7dEefOVD77jULgqJ4fKCmzqZBM4hILC9Cnc11x+fM7ZnTus2d4x
VQXOoHSHa5yiyTw9r0BWDyvbC/pXADo4nA/MNCzuik2W+JOtve6zLCWJgePZKuvx
zwY0rKDJAX4dqzPclABE+4E9FbTMzuB8t892INDWQt74RDO9SWPcX7RiObE0t0Yd
oBDdvuXwzddfEu9f6L9pPQ+58dDDlg==
=hV5H
-----END PGP SIGNATURE-----

--0TGN2duKhCYiG04TA8avalkRqpNrVCmIu--