Re: Patch RFC: Promise SATA300 TX4 hardware bug workaround.

Alexander Sabourenkov wrote:
> Hello.
>
> I have ported the workaround for the hardware bug that causes data
> corruption on Promise SATA300 TX4 cards to RELENG_7.
>
> Bug description:
> SATA300 TX4 hardware chokes if last PRD entry (in a dma transfer) is
> larger than 164 bytes. This was found while analysing vendor-supplied
> linux driver.
>
> Workaround:
> Split trailing PRD entry if it's larger that 164 bytes.
>
> Two supplied patches do fix problem on my machine.
>
> There is, however, a style problem with them. It seems like PRD entry
> count is limited at 256. I have not found a good way to guarantee that
> one entry is always available to do the split, thus the ugly solution of
> patching ata-dma.c.
>   
Good catch!

However from my quick glimpse at the Promise sources the limit seems to 
be 32 Dwords ie 32*4 = 128bytes.
I'll investigate further and ask Promise for the gory details, stay tuned...
I dont think the PRD count limitation is a real problem, I've newer seen 
that long a list and IIRC we newer do more than 64K transfers in one go 
(yet).
Anyhow I need to get checks in for that not just here...

Give me a few days and I'll get this figured out for 7-rel...

-Søren
>
> Patches, patched and original files are at http://lxnt.info/tx4/freebsd/.
>
>
> --- ata-chipset.c.orig	2007-11-02 01:05:49.000000000 +0300
> +++ ata-chipset.c	2007-11-02 01:05:49.000000000 +0300
> _at__at_ -142,6 +142,7 _at__at_
>  static int ata_promise_mio_command(struct ata_request *request);
>  static void ata_promise_mio_reset(device_t dev);
>  static void ata_promise_mio_dmainit(device_t dev);
> +static void ata_promise_mio_dmasetprd(void *xsc, bus_dma_segment_t
> *segs, int nsegs, int error);
>  static void ata_promise_mio_setmode(device_t dev, int mode);
>  static void ata_promise_sx4_intr(void *data);
>  static int ata_promise_sx4_command(struct ata_request *request);
> _at__at_ -185,7 +186,6 _at__at_
>  static int ata_check_80pin(device_t dev, int mode);
>  static int ata_mode2idx(int mode);
>
> -
>  /*
>   * generic ATA support functions
>   */
> _at__at_ -3759,8 +3759,44 _at__at_
>  static void
>  ata_promise_mio_dmainit(device_t dev)
>  {
> +    struct ata_channel *ch = device_get_softc(dev);
> +	
>      /* note start and stop are not used here */
>      ata_dmainit(dev);
> +
> +    if (ch->dma)
> +	ch->dma->setprd = ata_promise_mio_dmasetprd;
> +}
> +
> +static void
> +ata_promise_mio_dmasetprd(void *xsc, bus_dma_segment_t *segs, int
> nsegs, int error)
> +{
> +    #define PDC_MAXLASTSGSIZE 41*4
> +    struct ata_dmasetprd_args *args = xsc;
> +    struct ata_dma_prdentry *prd = args->dmatab;
> +    int i;
> +
> +    if ((args->error = error))
> +	return;
> +
> +    for (i = 0; i < nsegs; i++) {
> +	prd[i].addr = htole32(segs[i].ds_addr);
> +	prd[i].count = htole32(segs[i].ds_len);
> +    }
> +
> +    if (segs[i - 1].ds_len > PDC_MAXLASTSGSIZE) {
> +	/*
> +	printf("splitting trailing PRD of %ld (limit %d)\n", segs[i -
> 1].ds_len, PDC_MAXLASTSGSIZE);
> +	*/
> +	prd[i - 1].count = htole32(segs[i - 1].ds_len - PDC_MAXLASTSGSIZE);
> +	prd[i].count = htole32(PDC_MAXLASTSGSIZE);
> +	prd[i].addr = htole32(segs[i - 1].ds_addr + PDC_MAXLASTSGSIZE);
> +	i ++;
> +	nsegs ++;
> +    }
> +
> +    prd[i - 1].count |= htole32(ATA_DMA_EOT);
> +    args->nsegs = nsegs;
>  }
>
>  static void
>
> --- ata-dma.c.orig	2007-11-02 01:05:53.000000000 +0300
> +++ ata-dma.c	2007-11-02 01:05:53.000000000 +0300
> _at__at_ -113,7 +113,7 _at__at_
>      if
> (bus_dma_tag_create(ch->dma->dmatag,ch->dma->alignment,ch->dma->boundary,
>  			   ch->dma->max_address, BUS_SPACE_MAXADDR,
>  			   NULL, NULL, ch->dma->max_iosize,
> -			   ATA_DMA_ENTRIES, ch->dma->segsize,
> +			   ATA_DMA_ENTRIES - 1, ch->dma->segsize,
>  			   0, NULL, NULL, &ch->dma->data_tag))
>  	goto error;
>
>
>