From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 92A8FC10F09 for ; Fri, 8 Mar 2019 17:40:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5A80D20868 for ; Fri, 8 Mar 2019 17:40:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727010AbfCHRk3 (ORCPT ); Fri, 8 Mar 2019 12:40:29 -0500 Received: from mailproxy02.manitu.net ([217.11.48.66]:34180 "EHLO mailproxy02.manitu.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726934AbfCHRk2 (ORCPT ); Fri, 8 Mar 2019 12:40:28 -0500 Received: from [10.48.228.204] (x59cc82cc.dyn.telefonica.de [89.204.130.204]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: wg@grandegger.com) by mailproxy02.manitu.net (Postfix) with ESMTPSA id D037610200CB; Fri, 8 Mar 2019 18:44:28 +0100 (CET) Subject: Re: [PATCH v7 1/4] can: m_can: Create a m_can platform framework To: Dan Murphy , mkl@pengutronix.de, davem@davemloft.net Cc: linux-can@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20190305155220.14037-1-dmurphy@ti.com> <5065d6ba-f195-a695-77b1-b837cac1a199@grandegger.com> <6016c8aa-01b6-38d5-0e1f-3a999aae6a13@ti.com> <1f6f77c6-dcf2-6212-5d4e-1eb699e603f1@grandegger.com> <1e9acd4e-97ad-1d9c-44b6-1b2d1bbe8c0e@ti.com> From: Wolfgang Grandegger Openpgp: preference=signencrypt Autocrypt: addr=wg@grandegger.com; prefer-encrypt=mutual; keydata= mQINBFtEb5MBEAC5aRjs5jLwjbOaEE6rczZSqck7B3iGK8ldrV8HGSjxb1MAf4VbvDWrzXfA phEgX3e54AnYhnKcf6BA3J9TlSDdUAW7r/ijOFl+TehMz7holgjhlDK41acJ/klwXJotIqby bWqFgFw6o7b8hfbVzPi8Pz/+WOIKaDOb1Keb989mn253RF1yFakgvoQfCyAeVcnO5kcByW17 zbTEHsSduYi0Zir26Oedb2Vtas4SovrEXVh4e2dRdbEbHlI8po3Ih117CuGIPAe2RSfZKY88 8c9m+WsJKtrIDIMY+f5kcHG5mib++u1oTg7wjfFgTr925g2WjzT63YRibW8Vazot9yXquMo2 HYQStmnN9MuAkL/jslnxhGKNwTzpXv6FD2g/9hcLfSjaaCwGzj2j2ucJglJnO1n+ibVB14l2 JLVe+IKJaE1gvm2v9HPsE+o1P4O8I9iCiAbQ6BGUszHADOg7r8CeTQ+AOCypfEZ5l1Hwa3gw V+TtqyCU70U9LA0AKaDZ02vf0hFRWeXV/ErFq878GOXbbVMZu8G5aO0EcCBC75/KQnyi0WEl KVIcyTyxKel/Ext7vUFIkiA16JNWRpS85YDfe9CoEZcZK+nUU268j6Bp5a7MYaF/dZaLT+Du hLA82ry8IkPQvyV5yV+B0PwDM/w7de8zIzMy9YBXU8KGGDmgYQARAQABtCdXb2xmZ2FuZyBH cmFuZGVnZ2VyIDx3Z0BncmFuZGVnZ2VyLmNvbT6JAj8EEwECACkFAltEb5MCGyMFCQlmAYAH CwkIBwMCAQYVCAIJCgsEFgIDAQIeAQIXgAAKCRDwuz7LbZzIUhvED/4vTUqS0c/V5a4hc5Md u/8qkF7qg011tM0lXrZZxMQ8NrjdFuDhUefZ1q59QbLFU9da9D/CRVJUSx6BnY9jkR6lIm9l OGqS9ZlzubGXJCZhv1ONWPwY/i1RXTtauhRy+nkcyJk2Bzs5PWq1i4hWXpX//GfGUbCt+2bX 2+9bmHSPFtZ/MpIigS1E8RehIzlzqC/NCJspY8H0HKtLR6kpanRBYCuYSlBom/1LEP2MmXhh 9LgjQINp+jZJwnBj5L5JaUn/sg2WO+IiN6IphzyS2TvrlRhkhPJv5EOf0QmYzDgz5eU/h35x aCclLSJ0Go83GO0bXFGCzN86VreRgLRGTa7/x9VW05LiBdlsuLpG23IHM5f6p0WpYgE+jdri TrMued/DquQEcw/xNXpa3n9zTghLcWgcqGIdK3AE3yPjQBR3N6WoT4VOXnZjg6pyNHQ3W4qj LQgzJ3Tq2gPMhRLFcLXyk6V3rQ0ffn4LCXkFYVIBGAN8hHMOFeV6NESkUcEil6V4oOsLLGuJ XreFjAl1Cz3vIaVgzZEfub1z60DDM71lIr+UvWXLeMyKiSMWiJBPL3LUoUWmzpafaTJakDWm CEXa871Jlw7sy99MGVhiVG74JHjtPE6ontM1dKCP1+yT53TeGp1o/3Hj3sUielfDr5nV/kT6 p5zmgQN/1bJgV/3sKrkCDQRbRG+TARAA37mw9iosCWO5OtCrbvgJJwzOR3XrijVKi9KTNzDO NT2iy7teKP4+C+9why6iZhoJbBrTo56mbmI2nvfyOthxCa8nT14js8q0EgSMiyxXVeRvzEIQ sYcG4zgbGjwJ94Vrr5tMCFn5B6cYKJffTGmfY0D3b2V4GqaCGxVs3lWcQJeKl/raL8lp4YWz AI0jVx104W7rUbCTDvcSVfPqwM+9A6xaP4b1jwyYwGHgOTq6SeimRrGgM+UNtWqMU3+vUelG 8gKDyfIIo4IrceeHss5OuRREQZq5vNuzkeIY6faYWv65KT+IQ6EyC9UEGkMdcStfEsZO53Qq buA7Kha6lVViDM3vjGS+fnNq/od53dosWeWQ4O8M7Z6nxgp+EOPuJf041eKmIrcaRiXb+027 x4D0Kwv/xVsFa6cC2lkITWahENFIXwKOZ3imr2ZCtVF61qnm/GQ5P27JQKXMbPOM6wm0EjJ1 9t2EkSpgVHI0Cd0ldxD4eaGNwpeHJ5WGGzZrOE7PCcRziJX0qO/FpLjTQ6scf+bPACgduY71 AwXyA24mg7F2vK+Vth+Yp7MlgwYBMUy6D140jrkWrcRxKYfW1BgcKpbG/dh5DhUAvoOzFD7i zHrGK5FhzqJDBwKk7n9jGohf/MJWs2UKai/u4ogZBhhD5JPR8GG6VzO4snWisFLFuAEAEQEA AYkCJQQYAQIADwUCW0RvkwIbDAUJCWYBgAAKCRDwuz7LbZzIUkA3D/wJOvcQ7rTeoRiamOIB kD4n2Jsv8Vti/XfM0DTmhfnWL4y96VzSzNfl+EHAwXE4161qnXxTHnFK1hq7QklNdDiGW3iH nKZUyHUTnlUlCocv8jWtlqrpH0XVtF12JET65mE14Hga6BQ4ECXwU2GcP3202A55EzMj31b/ 59GD3CDIJy7bjQi+pIRuA9ZQRsFas7Od7AWO/nFns2wJ6AJkjXdCUCZ4iOuf82gLK9olDSmd H73Epc6l3jca62L2Lzei405LQSsfOZ06uH2aGPUJX4odUlEF6arm2j+9Q8Vyi4CJ316f2kAa sl7LhAwZtaj8hjl/PUWfd5w47dUBDUZjIRYcdM2TTU3Spgvg3zqXUzur5+r0jkUl2naeiSB1 vwjfIwnPqZOVr9FAXuLbAdUyCCC0ohGLrq5Nsc1A02rxpQHRxTSm2FOdn2jYvuD7JUgkhmUh /TXb8aL6A4hfX7oV4tGq7nSmDOCmgWRmAHAGp85fVq2iylCxZ1kKi8EYCSa28eQzetukFbAx JwmcrUSaCOK+jpHlNY0PkghSIzAE/7Se+c37unJ39xJLkrgehLYmUF7cBeNWhfchu4fAJosM 5mXohGkBKcd5YYmF13imYtAG5/VSmBm/0CFNGFO49MVTNGXGBznrPrWwtPZNwjJdi7JrvEbm 8QEfHnPzgykCs2DOOQ== Message-ID: <2026f4ff-31de-3040-0872-5e9d01cc5aa5@grandegger.com> Date: Fri, 8 Mar 2019 18:40:24 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <1e9acd4e-97ad-1d9c-44b6-1b2d1bbe8c0e@ti.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Dan, Am 08.03.19 um 18:25 schrieb Dan Murphy: > On 3/8/19 11:08 AM, Wolfgang Grandegger wrote: >> Hello, >> >> Am 08.03.19 um 16:48 schrieb Dan Murphy: >>> Wolfgang >>> >>> On 3/8/19 8:41 AM, Wolfgang Grandegger wrote: >>>> Hello Dan, >>>> >>>> thinking more about it... >>>> >>>> Am 08.03.19 um 14:29 schrieb Wolfgang Grandegger: >>>>> Hello Dan, >>>>> >>>>> Am 08.03.19 um 13:44 schrieb Dan Murphy: >>>>>> Wolfgang >>>>>> >>>>>> On 3/8/19 4:10 AM, Wolfgang Grandegger wrote: >>>>>>> Hallo Dan, >>>>>>> >>>>>>> Am 05.03.19 um 16:52 schrieb Dan Murphy: >>>>>>>> Create a m_can platform framework that peripherial >>>>>>>> devices can register to and use common code and register sets. >>>>>>>> The peripherial devices may provide read/write and configuration >>>>>>>> support of the IP. >>>>>>>> >>>>>>>> Signed-off-by: Dan Murphy >>>>>>>> --- >>>>>>>> >>>>>>>> >>>>>>>> v7 - Fixed remaining new checkpatch issues, removed CSR setting, fixed tx hard >>>>>>>> start function to return tx_busy, and renamed device callbacks - https://lore.kernel.org/patchwork/patch/1047220/ >>>>>>>> >>>>>>>> v6 - Squashed platform patch to this patch for bissectablity, fixed coding style >>>>>>>> issues, updated Kconfig help, placed mcan reg offsets back into c file, renamed >>>>>>>> priv->skb to priv->tx_skb and cleared perp interrupts at ISR start - >>>>>>>> Patch 1 comments - https://lore.kernel.org/patchwork/patch/1042446/ >>>>>>>> Patch 2 comments - https://lore.kernel.org/patchwork/patch/1042442/ >>>>>>>> >>>>>>>> drivers/net/can/m_can/Kconfig | 13 +- >>>>>>>> drivers/net/can/m_can/Makefile | 1 + >>>>>>>> drivers/net/can/m_can/m_can.c | 700 +++++++++++++------------ >>>>>>>> drivers/net/can/m_can/m_can.h | 110 ++++ >>>>>>>> drivers/net/can/m_can/m_can_platform.c | 202 +++++++ >>>>>>>> 5 files changed, 682 insertions(+), 344 deletions(-) >>>>>>>> create mode 100644 drivers/net/can/m_can/m_can.h >>>>>>>> create mode 100644 drivers/net/can/m_can/m_can_platform.c >>>>>>>> >>>>>>>> diff --git a/drivers/net/can/m_can/Kconfig b/drivers/net/can/m_can/Kconfig >>>>>>>> index 04f20dd39007..f7119fd72df4 100644 >>>>>>>> --- a/drivers/net/can/m_can/Kconfig >>>>>>>> +++ b/drivers/net/can/m_can/Kconfig >>>>>>>> @@ -1,5 +1,14 @@ >>>>>>>> config CAN_M_CAN >>>>>>>> + tristate "Bosch M_CAN support" >>>>>>>> + ---help--- >>>>>>>> + Say Y here if you want support for Bosch M_CAN controller framework. >>>>>>>> + This is common support for devices that embed the Bosch M_CAN IP. >>>>>>>> + >>>>>>>> +config CAN_M_CAN_PLATFORM >>>>>>>> + tristate "Bosch M_CAN support for io-mapped devices" >>>>>>>> depends on HAS_IOMEM >>>>>>>> - tristate "Bosch M_CAN devices" >>>>>>>> + depends on CAN_M_CAN >>>>>>>> ---help--- >>>>>>>> - Say Y here if you want to support for Bosch M_CAN controller. >>>>>>>> + Say Y here if you want support for IO Mapped Bosch M_CAN controller. >>>>>>>> + This support is for devices that have the Bosch M_CAN controller >>>>>>>> + IP embedded into the device and the IP is IO Mapped to the processor. >>>>>>>> diff --git a/drivers/net/can/m_can/Makefile b/drivers/net/can/m_can/Makefile >>>>>>>> index 8bbd7f24f5be..057bbcdb3c74 100644 >>>>>>>> --- a/drivers/net/can/m_can/Makefile >>>>>>>> +++ b/drivers/net/can/m_can/Makefile >>>>>>>> @@ -3,3 +3,4 @@ >>>>>>>> # >>>>>>>> >>>>>>>> obj-$(CONFIG_CAN_M_CAN) += m_can.o >>>>>>>> +obj-$(CONFIG_CAN_M_CAN_PLATFORM) += m_can_platform.o >>>>>>>> diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c >>>>>>>> index 9b449400376b..a60278d94126 100644 >>>>>>>> --- a/drivers/net/can/m_can/m_can.c >>>>>>>> +++ b/drivers/net/can/m_can/m_can.c >>>>>>> >>>>>>> ... snip... >>>>>>> >>>>>>>> +static netdev_tx_t m_can_start_xmit(struct sk_buff *skb, >>>>>>>> + struct net_device *dev) >>>>>>>> +{ >>>>>>>> + struct m_can_priv *priv = netdev_priv(dev); >>>>>>>> + >>>>>>>> + if (can_dropped_invalid_skb(dev, skb)) >>>>>>>> + return NETDEV_TX_OK; >>>>>>>> + >>>>>>>> + if (priv->is_peripherial) { >>>>>>>> + if (priv->tx_skb) { >>>>>>>> + netdev_err(dev, "hard_xmit called while tx busy\n"); >>>>>>>> + return NETDEV_TX_BUSY; >>>>>>>> + } >>>>>>> >>>>>>> The problem with that approach is, that the upper layer will try to >>>>>>> resubmit the current "skb" but not the previous "tx_skb". And the >>>>>>> previous "tx_skb" has not been freed yet. I would just drop and free the >>>>>>> skb and return NETDEV_TX_OK in m_can_tx_handler() for peripheral devices >>>>>>> (like can_dropped_invalid_skb() does). >>>>>>> >>>>>> >>>>>> OK. >>>>>> >>>>>> So would this also be a bug in the hi3110 and mcp251x drivers (line 521) as well because besides checking tx_length >>>>>> this is how these drivers are written. >>>>> >>>>> This is different. When entering the "start_xmit" routine, the previous >>>>> TX is still in progress. It will (hopefully) complete soon. Therefore >>>>> returning NETDEV_TX_BUSY is OK. The "start_xmit" routine will be >>>>> recalled soon with the same "skb". That scenario should/could also not >>>>> happen. >>>> >>>> In principle, this also applies to the m_can peripheral devices. If >>>> tx_skb is not NULL, the TX is still in progress and returning >>>> NETDEV_TX_BUSY is just fine. >>>> >>>>> >>>>> In contrast, in "m_can_tx_handler()", the skb could not be handled >>>>> because the FIFO is full. The "start_xmit" routine for peripheral >>>>> devices for that skb already returned NETDEV_TX_OK. Therefore the only >>>>> meaningful action is to drop the skb. Also this error should not happen >>>>> and if, something is going really wrong. Therefore I think, a >>>>> WARN_ONCE() would be even more appropriate. But that should be a >>>>> separate patch. >>>> >>>> But that's a different issue/error. The tx_skb cannot be processed in >>>> "m_can_tx_handler()". Either we drop it or we re-queue it (retry later). >>>> >>> >>> OK I am a bit confused on this. Are you saying this is not an issue? >>> Or are you saying I need to check for tx_len like the other code? >> >> If you check for tx_skb in the "start_xmit" routine like the hi3110 and >> mcp251x, it will work the same way. But only, if the "tx_handler()" has >> fully processed the message. It simple means, the TX is still in >> progress and will complete soon. But in "m_can_tx_handler()" we return >> without handling the message! It will never be sent and freed. Or will >> the "m_can_tx_handler()" retry? >> > > I am not seeing where we are not handling the message in the m_can_tx_handler() static void m_can_tx_handler(struct m_can_classdev *priv) { ... /* Check if FIFO full */ if (m_can_tx_fifo_full(priv)) { /* This shouldn't happen */ netif_stop_queue(dev); netdev_warn(dev, "TX queue active although FIFO is full."); return; } We simply return here. When is the message (tx_skb) processed (sent or freed)? What happens with tx_skb? For the hi3110, we have: static void hi3110_tx_work_handler(struct work_struct *ws) { struct hi3110_priv *priv = container_of(ws, struct hi3110_priv, tx_work); struct spi_device *spi = priv->spi; struct net_device *net = priv->net; struct can_frame *frame; mutex_lock(&priv->hi3110_lock); if (priv->tx_skb) { if (priv->can.state == CAN_STATE_BUS_OFF) { hi3110_clean(net); } else { frame = (struct can_frame *)priv->tx_skb->data; hi3110_hw_tx(spi, frame); priv->tx_len = 1 + frame->can_dlc; can_put_echo_skb(priv->tx_skb, net, 0); priv->tx_skb = NULL; } } mutex_unlock(&priv->hi3110_lock); } Either the tx_skb is sent or cleanup (dropped and freed) in case of bus-off. Also "hi3110_clean" sets "priv->tx_skb = NULL"! The "tx_len" handles a pending "echo_skb". > > In the peripheral code the work is queued up. And the work thread is m_can_tx_work_queue. > > This in turn calls the m_can_tx_handler and the worker is blocked until return which means the message > would have been processed. > > If there is no issue and the handler returns OK then the skb is set to null. > Otherwise the only other time that the skb will not be null is if the FIFO was full. > > Plus there can only be one work queue at a time so the processing is synchronous. > If the upper layer decides to send another packet before the prior one is complete then it will get > a TX busy return. > > IOmapped calls are blocked on return so this is not an issue. We cannot do it the same way with peripherals due to the > atomic context of the request. Wolfgang.