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Re: Regarding AHCI_MAX_SG and (ATA_HORKAGE_MAX_SEC_1024)

From Tom Yan <tom.ty89@gmail.com>
Newsgroups linux.kernel
Subject Re: Regarding AHCI_MAX_SG and (ATA_HORKAGE_MAX_SEC_1024)
Date 2016-08-10 22:20 +0200
Message-ID <s4Hw7-YV-61@gated-at.bofh.it> (permalink)
References <s3x5M-4So-9@gated-at.bofh.it> <s4sno-88Q-25@gated-at.bofh.it> <s4G72-8uN-149@gated-at.bofh.it> <s4G72-8uN-151@gated-at.bofh.it> <s4G72-8uN-147@gated-at.bofh.it>
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On 10 August 2016 at 15:41, David Milburn <dmilburn@redhat.com> wrote:
> Hi,
>
> The 168 makes AHCI_CMD_TBL_SZ equal to 2816
>
> AHCI_CMD_TBL_SZ = AHCI_CMD_TBL_HDR_SZ + (AHCI_MAX_SG * 16)
> AHCI_CMD_TBL_SZ = 128 + (168 * 16)
>
> I think if you add in AHCI_CMD_SLOT_SZ (1024) and AHCI_RX_FIS_SZ (256)
> the DMA is 4K aligned, I think that is where the 168 came from.

Looks like the right guess. Though AHCI_PORT_PRIV_DMA_SZ is not:

AHCI_CMD_SLOT_SZ (1024) + AHCI_CMD_TBL_SZ (2816) + AHCI_RX_FIS_SZ (256) = 4096

but:

AHCI_CMD_SLOT_SZ (1024) + AHCI_CMD_TBL_AR_SZ (2816 * 32 = 90112) +
AHCI_RX_FIS_SZ (256) = 91392

and AHCI_PORT_PRIV_FBS_DMA_SZ is:

AHCI_CMD_SLOT_SZ (1024) + AHCI_CMD_TBL_AR_SZ (2816 * 32 = 90112) +
AHCI_RX_FIS_SZ * 16 (4096) = 95232

>
> Thanks,
> David
>
>

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Thread

Regarding AHCI_MAX_SG and (ATA_HORKAGE_MAX_SEC_1024) Tom Yan <tom.ty89@gmail.com> - 2016-08-07 16:20 +0200
  Re: Regarding AHCI_MAX_SG and (ATA_HORKAGE_MAX_SEC_1024) Tejun Heo <tj@kernel.org> - 2016-08-10 05:30 +0200
    Re: Regarding AHCI_MAX_SG and (ATA_HORKAGE_MAX_SEC_1024) David Milburn <dmilburn@redhat.com> - 2016-08-10 20:10 +0200
      Re: Regarding AHCI_MAX_SG and (ATA_HORKAGE_MAX_SEC_1024) David Milburn <dmilburn@redhat.com> - 2016-08-10 21:40 +0200
      Re: Regarding AHCI_MAX_SG and (ATA_HORKAGE_MAX_SEC_1024) Tom Yan <tom.ty89@gmail.com> - 2016-08-10 22:20 +0200
    Re: Regarding AHCI_MAX_SG and (ATA_HORKAGE_MAX_SEC_1024) Tejun Heo <tj@kernel.org> - 2016-08-10 21:10 +0200
    Re: Regarding AHCI_MAX_SG and (ATA_HORKAGE_MAX_SEC_1024) Tom Yan <tom.ty89@gmail.com> - 2016-08-10 21:20 +0200

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