From: Ulrich Hecht <uli@fpond.eu>
To: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>,
linux-renesas-soc@vger.kernel.org
Subject: Re: [PATCH RFC 0/4] mmc: host: renesas_sdhi_sys_dmac: change dma_buswidth
Date: Tue, 26 Nov 2019 11:45:25 +0100 (CET) [thread overview]
Message-ID: <1619526348.1354132.1574765125512@webmail.strato.com> (raw)
In-Reply-To: <1574403231-18512-1-git-send-email-yoshihiro.shimoda.uh@renesas.com>
> On November 22, 2019 at 7:13 AM Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> wrote:
>
>
> This patch can improve performance when a sd card transfer size
> is multiples of 32 like a sd memory card. However, this may
> disimprove performance when a sd card transfer size is not
> multiples of 32 because this patch uses PIO instead of SYS-DMAC.
I have logged the DMA transfer sizes of a Marvell SD8897 WiFi/BT chip, and there transfers that are not multiples of 32 are infrequent (every second or so) and small (184 bytes); all large transfers are multiples of 32.
Would it be practical to switch the DMA bus width down if odd sizes are encountered, and back up again otherwise?
CU
Uli
next prev parent reply other threads:[~2019-11-26 10:48 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-22 6:13 [PATCH RFC 0/4] mmc: host: renesas_sdhi_sys_dmac: change dma_buswidth Yoshihiro Shimoda
2019-11-22 6:13 ` [PATCH RFC 1/4] mmc: host: renesas_sdhi_sys_dmac: Use dma_buswidth instead of hardcoded value Yoshihiro Shimoda
2019-11-26 10:45 ` Ulrich Hecht
2019-11-22 6:13 ` [PATCH RFC 2/4] mmc: host: renesas_sdhi_sys_dmac: Do not fall back to PIO Yoshihiro Shimoda
2019-11-26 10:45 ` Ulrich Hecht
2019-11-22 6:13 ` [PATCH RFC 3/4] mmc: host: renesas_sdhi_sys_dmac: add DMACR setting Yoshihiro Shimoda
2019-11-26 10:46 ` Ulrich Hecht
2019-12-02 8:19 ` Yoshihiro Shimoda
2019-11-22 6:13 ` [PATCH RFC 4/4] mmc: host: renesas_sdhi_sys_dmac: Set dma_buswidth value to 32 byte Yoshihiro Shimoda
2019-11-26 10:46 ` Ulrich Hecht
2019-11-28 21:07 ` Wolfram Sang
2019-12-02 8:38 ` Yoshihiro Shimoda
2019-12-02 8:54 ` Wolfram Sang
2019-11-26 10:45 ` Ulrich Hecht [this message]
2019-12-02 8:09 ` [PATCH RFC 0/4] mmc: host: renesas_sdhi_sys_dmac: change dma_buswidth Yoshihiro Shimoda
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