On 07/31/2018 08:30 AM, Pankaj Bansal wrote: > >> -----Original Message----- >> From: Marc Kleine-Budde [mailto:mkl@xxxxxxxxxxxxxx] >> Sent: Monday, July 30, 2018 8:21 PM >> To: Pankaj Bansal <pankaj.bansal@xxxxxxx>; linux-can@xxxxxxxxxxxxxxx >> Subject: Re: [PATCH 5/6] net: can: flexcan: split the Message Buffer RAM >> area >> >> On 07/30/2018 06:07 PM, Pankaj Bansal wrote: >>> The message buffer RAM area is not a contiguous 1KB area but 2 >>> partitions of 512 bytes each. Till now, we used Message buffers with >>> payload size 8 bytes, which translates to 32 MBs per partition and no >>> spare space is left in any partition. >>> However, in upcoming SOC LX2160A the message buffers can have >> payload >>> size greater than 8 bytes. This results in less than 32 MBs per >>> partition and some empty area is left at the end of each >>> partition.This empty area should not be accessed. >>> Therefore, split the Message Buffer RAM area into two partitions. >>> >>> Signed-off-by: Pankaj Bansal <pankaj.bansal@xxxxxxx> >>> --- >>> drivers/net/can/flexcan.c | 66 ++++++++++++++++++++++++++++--------- >>> 1 file changed, 50 insertions(+), 16 deletions(-) >>> >>> diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c >>> index 15fa983a8237..147405e703f0 100644 >>> --- a/drivers/net/can/flexcan.c >>> +++ b/drivers/net/can/flexcan.c >>> @@ -223,7 +223,8 @@ struct flexcan_regs { >>> u32 rxfgmask; /* 0x48 */ >>> u32 rxfir; /* 0x4c */ >>> u32 _reserved3[12]; /* 0x50 */ >>> - u32 mb[256]; /* 0x80 */ >>> + u32 mb1[128]; /* 0x80 */ >>> + u32 mb2[128]; /* 0x280 */ >>> /* FIFO-mode: >>> * MB >>> * 0x080...0x08f 0 RX message buffer >>> @@ -262,6 +263,8 @@ struct flexcan_priv { >>> struct flexcan_mb __iomem *tx_mb; >>> struct flexcan_mb __iomem *tx_mb_reserved; >>> u8 tx_mb_idx; >>> + u8 mb_count_block1; >>> + u8 mb_count_block2; >> >> What's the difference between these two? > > This tells the number of Message Buffers in each RAM block. > > suppose Block0 is configured to 8 bytes payload, Block1 to 16 bytes, > than the following table indicates how the Message Buffers will be > arranged into RAM. Does this make any sense in a real world scenario? How do you plan to configure these partitions? > RAM partition example > ________________________________________________________________________________ > RAM block | Payload size | Number of MBs in the RAM block | Message Buffer range > 0 | 8 | 32 | 0 to 31 > 1 | 16 | 21 |32 to 52 > -------------------------------------------------------------------------------- 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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