linux-kernel - Re: [PATCH v5 2/5] can: m_can: Migrate the m

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Date:   Thu, 28 Feb 2019 20:41:45 +0100
From:   Wolfgang Grandegger <wg@...ndegger.com>
To:     Dan Murphy <dmurphy@...com>, mkl@...gutronix.de,
        davem@...emloft.net
Cc:     linux-can@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 2/5] can: m_can: Migrate the m_can code to use the
 framework

Hello Dan,

Am 28.02.19 um 18:57 schrieb Dan Murphy:
> Wolfgang
> 
> On 2/28/19 11:33 AM, Wolfgang Grandegger wrote:
>> Am 14.02.19 um 19:27 schrieb Dan Murphy:
>>> Migrate the m_can code to use the m_can_platform framework
>>> code.
>>>
>>> Signed-off-by: Dan Murphy <dmurphy@...com>
>>> ---
>>>
>>> v5 - Updated copyright, change m_can_classdev to m_can_priv, removed extra
>>> KCONFIG flag - https://lore.kernel.org/patchwork/patch/1033095/
>>>
>>>  drivers/net/can/m_can/Kconfig  |   8 +-
>>>  drivers/net/can/m_can/Makefile |   1 +
>>>  drivers/net/can/m_can/m_can.c  | 745 ++++++++++++++++-----------------
>>>  3 files changed, 367 insertions(+), 387 deletions(-)
>>>
>>> diff --git a/drivers/net/can/m_can/Kconfig b/drivers/net/can/m_can/Kconfig
>>> index 04f20dd39007..66e31022a5fa 100644
>>> --- a/drivers/net/can/m_can/Kconfig
>>> +++ b/drivers/net/can/m_can/Kconfig
>>> @@ -1,5 +1,11 @@
>>>  config CAN_M_CAN
>>> +	tristate "Bosch M_CAN support"
>>> +	---help---
>>> +	  Say Y here if you want to support for Bosch M_CAN controller.
>>
>> Typo?
>>
> 
> Maybe like you pointed out to update the help.

I was just not sure if it's correct English... but you know better!

> 
>>> +
>>> +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.
>>
>> Please update the help.
> 
> Ack
>>
>>> 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..2ceccb870557 100644
>>> --- a/drivers/net/can/m_can/m_can.c
>>> +++ b/drivers/net/can/m_can/m_can.c
... snip ...
>>> @@ -924,6 +885,9 @@ static irqreturn_t m_can_isr(int irq, void *dev_id)
>>>  		}
>>>  	}
>>>  
>>> +	if (priv->ops->clr_dev_interrupts)
>>> +		priv->ops->clr_dev_interrupts(priv);
>>
>> post_irq _handler?
>>
> 
> I can clear them on entry as well

OK!

...snip...

>>> -	niso_timeout = readl_poll_timeout((priv->base + M_CAN_CCCR), cccr_poll,
>>> -					  (cccr_poll == cccr_reg), 0, 10);
>>> +	for (i = 0; i <= 10; i++) {
>>> +		cccr_poll = m_can_read(priv, M_CAN_CCCR);
>>> +		if (cccr_poll == cccr_reg)
>>> +			niso_timeout = 0;
>>> +	}
>>
>> There is no break and delay in the loop? What was the reason why you
>> can't use readl_poll_timeout()?
>>
> 
> OK a break if NISO is supported then and probably could add a 1us delay original code on
> line 1232 had no delay but timeout at 10us.
> 
> readl_poll_timeout is for iomapped devices.  How would this work for peripherial devices?

Well, it takes much more time to read the register via SPI... maybe using

	if (priv->is_peripherial) ...

to handle the different timings would make sense here.

>>>  
>>>  	/* Clear NISO */
>>>  	cccr_reg &= ~(CCCR_NISO);
>>> @@ -1242,107 +1210,95 @@ static bool m_can_niso_supported(const struct m_can_priv *priv)
>>>  	return !niso_timeout;
>>>  }
... snip...

>>> -static netdev_tx_t m_can_start_xmit(struct sk_buff *skb,
>>> -				    struct net_device *dev)
>>> +static void m_can_tx_handler(struct m_can_priv *priv)
>>>  {
>>> -	struct m_can_priv *priv = netdev_priv(dev);
>>> -	struct canfd_frame *cf = (struct canfd_frame *)skb->data;
>>> +	struct canfd_frame *cf = (struct canfd_frame *)priv->skb->data;
>>> +	struct net_device *dev = priv->net;
>>> +	struct sk_buff *skb = priv->skb;
>>
>> Maybe "tx_skb" is a clearer member name..
> 
> Again this was named skb to minimize deltas from original code.

I mean "priv->tx_skb"!

> skb was passed into the start_xmit function and used throughout the function.
> 
> Since there was little delta in this function I opt'd to keep the names as is.
> 

Wolfgang.