On Tue, Jul 15, 2014 at 10:46:32AM +0200, Marc Kleine-Budde wrote:
> On 07/15/2014 10:26 AM, Dong Aisheng wrote:
> >>>>> +static void m_can_read_fifo(const struct net_device *dev, struct can_frame *cf,
> >>>>> + u32 rxfs)
> >>>>> +{
> >>>>> + struct m_can_priv *priv = netdev_priv(dev);
> >>>>> + u32 flags, fgi;
> >>>>> +
> >>>>> + /* calculate the fifo get index for where to read data */
> >>>>> + fgi = (rxfs & RXFS_FGI_MASK) >> RXFS_FGI_OFF;
> >>>>> + flags = m_can_fifo_read(priv, fgi, 0x0);
> >>>> ^^^
> >>>>
> >>>> Can you introduce an enum for the offsets, please adjust the signature
> >>>> of m_can_fifo_read() accordingly.
> >>>>
> >>>
> >>> I wonder enum may not be suitable.
> >>> The Rx Buffer and FIFO Element is as follows:
> >>> 31 24 23 16 15 8 7 0
> >>> R0 ESI XTD RTR ID[28:0]
> >>
> >> M_CAN_FIFO_ID
> >>
> >>> R1 ANMF FIDX[6:0] res EDL BRS DLC[3:0] RXTS[15:0]
> >>
> >> M_CAN_FIFO_DLC
> >>
> >>> R2 DB3[7:0] DB2[7:0] DB1[7:0] DB0[7:0]
> >>> R3 DB7[7:0] DB6[7:0] DB5[7:0] DB4[7:0]
> >>
> >> M_CAN_FIFO_DATA0
> >> M_CAN_FIFO_DATA1
> >>
> >
> > You mean as follows?
> > enum m_can_fifo {
> > M_CAN_FIFO_ID = 0,
> > M_CAN_FIFO_DLC,
> = 0x4,
> > M_CAN_FIFO_DATA0,
> = 0x8,
> > M_CAN_FIFO_DATA1,
> = 0xc,
> > };
> >
> > static inline u32 m_can_fifo_read(const struct m_can_priv *priv,
> > u32 fgi, enum m_can_fifo fifo)
> > {
> > return readl(priv->mram_base + priv->mcfg[MRAM_RXF0].off +
> > fgi * RXF0_ELEMENT_SIZE + fifo * 0x4);
> > }
>
> without the * 0x4
>
> > id = m_can_fifo_read(priv, fgi, M_CAN_FIFO_ID);
> >
> > The problem is when adding long frames support, it becomes:
> > enum m_can_fifo {
> > M_CAN_FIFO_ID = 0,
> > M_CAN_FIFO_DLC,
> > M_CAN_FIFO_DATA0,
> > M_CAN_FIFO_DATA1,
> > ....
> > M_CAN_FIFO_DATA15,
> > };
>
> #define M_CAN_FIFO_DATA(n)
> (enum m_can_fifo)(M_CAN_FIFO_DATA_0 + (n) << 2)
>
This is a bit strange using and we may still have to define other M_CAN_FIFO_DATAx
to avoid the enum value exceeds the defined range.
enum m_can_fifo {
M_CAN_FIFO_ID = 0,
M_CAN_FIFO_DLC = 0x4,
M_CAN_FIFO_DATA0 = 0x8,
M_CAN_FIFO_DATA1 = 0xc,
....
M_CAN_FIFO_DATA15 = 0xc,
};
However, actually we will not use them at all after introducing M_CAN_FIFO_DATA(n).
If that, why we still need define them in enum?
Comparing to this way, why not simply just do as follows:
#define M_CAN_FIFO_ID 0x0
#define M_CAN_FIFO_DLC 0x4
#define M_CAN_FIFO_DATA(n) (0x8 + (n) << 2)
What do you think?
> > But it's useless because we may not use enum to read fifo data anymore.
> > It's not suitable to read fifo one by one:
> > m_can_fifo_read(priv, fgi, M_CAN_FIFO_DATA0);
> > m_can_fifo_read(priv, fgi, M_CAN_FIFO_DATA1);
> > ..
> > m_can_fifo_read(priv, fgi, M_CAN_FIFO_DATA15);
> >
> >
> > Instead, we may read data according to real dlc value within a for loop like:
> > #define M_CAN_FIFO(n) (n * 0x4)
> > id = m_can_fifo_read(priv, fgi, M_CAN_FIFO(0));
> > dlc = m_can_fifo_read(priv, fgi, M_CAN_FIFO(1));
> > for (i = 0; dlc > 0; dlc -= 0x4, i++) {
> > ....
> > data[i] = m_can_fifo_read(priv, fgi, M_CAN_FIFO(i + 2));
> > }
>
> id = m_can_fifo_read(priv, fgi, M_CAN_FIFO_ID);
> dlc = m_can_fifo_read(priv, fgi, M_CAN_FIFO_DLC);
> for (i = 0; i <= dlc; i++)
> data[i] = m_can_fifo_read(priv, fgi, M_CAN_FIFO_DATA(i));
Does it work?
The dlc is in bytes while m_can_fifo_read is read in words.
Regards
Dong Aisheng
>
> > So i'm not sure define that enum now is really needed.
>
> [...]
>
> >>>>> +static int m_can_handle_lec_err(struct net_device *dev,
> >>>>> + enum m_can_lec_type lec_type)
> >>>>> +{
> >>>>> + struct m_can_priv *priv = netdev_priv(dev);
> >>>>> + struct net_device_stats *stats = &dev->stats;
> >>>>> + struct can_frame *cf;
> >>>>> + struct sk_buff *skb;
> >>>>> +
> >>>>> + /* early exit if no lec update */
> >>>>> + if (lec_type == LEC_UNUSED)
> >>>>> + return 0;
> >>>>
> >>>> I think this is not needed, as checked by the only caller.
> >>>
> >>> You mean move it to caller as follows?
> >>> /* handle lec errors on the bus */
> >>> if ((psr & LEC_UNUSED) && ((psr & LEC_UNUSED)!= LEC_UNUSED) &&
> >>
> >> yes - or something like this:
> >>
> >> static inline bool is_lec(u32 psr)
> >> {
> >> u32 psr &= LEC_UNUSED
> >>
> >> return psr && (psr != LEC_UNUSED)
> >> }
> >>
> >> if ((priv->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING) &&
> >> is_lec(psr)) {
> >> }
> >>
> >
> >
> > Looks fine.
> > Maybe is_lec_err(u32 psr) better? :-)
>
> Yes, is_lec() was just a random placeholder :) Descriptive function
> names are always preferred.
>
> 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 |
>
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