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From: Wolfram Sang <wsa@the-dreams.de>
To: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Cc: ulf.hansson@linaro.org, wsa+renesas@sang-engineering.com,
	linux-mmc@vger.kernel.org, linux-renesas-soc@vger.kernel.org
Subject: Re: [PATCH v2 2/2] mmc: renesas_sdhi: use multiple segments if possible
Date: Mon, 13 May 2019 11:00:54 +0200	[thread overview]
Message-ID: <20190513090054.GA15744@kunai> (raw)
In-Reply-To: <1557721744-30545-3-git-send-email-yoshihiro.shimoda.uh@renesas.com>

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Hi Shimoda-san,

thank you for this update!

> +static void renesas_sdhi_init_card(struct mmc_host *mmc, struct mmc_card *card)
> +{
> +	struct tmio_mmc_host *host = mmc_priv(mmc);
> +
> +	if (host->pdev->dev.iommu_group &&

I wonder if I am too cautious, but maybe we should have another
condition here to be checked first, namely "host->mmc->max_segs < 512"?

> +	    (mmc_card_mmc(card) || mmc_card_sd(card)))
> +		host->mmc->max_segs = 512;
> +	else
> +		host->mmc->max_segs = host->pdata->max_segs;

max_segs can be 0, so we should probably have:

 +		host->mmc->max_segs = host->pdata->max_segs ?: 32;

That also means, for the sys-dmac and Gen2, we then use 512 for the
IOMMU case and 32 (default TMIO value) for the non IOMMU case. My
understanding is that SYS DMAC can handle 512 in both cases. Maybe it
makes sense then to make an incremental patch setting the max_segs value
explicitly to 512 in the sys-dmac driver for Gen2?

Kind regards,

   Wolfram


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  reply	other threads:[~2019-05-13  9:00 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-13  4:29 [PATCH v2 0/2] mmc: renesas_sdhi: improve performance by using IOMMU Yoshihiro Shimoda
2019-05-13  4:29 ` [PATCH v2 1/2] mmc: tmio: No memory size limitation if runs on IOMMU Yoshihiro Shimoda
2019-05-13  4:29 ` [PATCH v2 2/2] mmc: renesas_sdhi: use multiple segments if possible Yoshihiro Shimoda
2019-05-13  9:00   ` Wolfram Sang [this message]
2019-05-13  9:46     ` Yoshihiro Shimoda
2019-05-13 11:34       ` Yoshihiro Shimoda
2019-05-13 13:54         ` Wolfram Sang
2019-05-14  6:05       ` Yoshihiro Shimoda
2019-05-21 21:57         ` Wolfram Sang
2019-05-22  5:11           ` Yoshihiro Shimoda

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