linux-kernel - Re: [PATCH] mmc: mtk-sd: reduce CIT for better performance

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Date:   Wed, 10 May 2023 01:44:59 +0000
From:   Wenbin Mei (梅文彬) 
        <Wenbin.Mei@...iatek.com>
To:     "ulf.hansson@...aro.org" <ulf.hansson@...aro.org>
CC:     "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "angelogioacchino.delregno@...labora.com" 
        <angelogioacchino.delregno@...labora.com>,
        Chaotian Jing (井朝天) 
        <Chaotian.Jing@...iatek.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mmc: mtk-sd: reduce CIT for better performance

On Tue, 2023-05-09 at 11:29 +0200, Ulf Hansson wrote:
> External email : Please do not click links or open attachments until
> you have verified the sender or the content.
> 
> 
> On Wed, 19 Apr 2023 at 08:30, Wenbin Mei <wenbin.mei@...iatek.com>
> wrote:
> > 
> > CQHCI_SSC1 indicates to CQE the polling period to use when using
> > periodic SEND_QUEUE_STATUS(CMD13) polling.
> > The default value is 0x1000, now change it to 0x40, which can
> > improve the performance of some eMMC devices.
> 
> Rather than just providing hexadecimal numbers, would you mind
> explaining a bit what it translates into?
> 
> For example, "the default value 0x1000 that corresponds to x ms...,
> ... lets' decrease it to 0x40 that corresponds to x ms".
> 
> Moreover, it would be nice to have a comment in the code too,
> explaining what 0x40 translates into.
> 
> Other than this, this looks good to me.
> 
> Kind regards
> Uffe
> 
Thanks for your review.
I will follow your comment in next change.
> > 
> > Signed-off-by: Wenbin Mei <wenbin.mei@...iatek.com>
> > ---
> >  drivers/mmc/host/mtk-sd.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/drivers/mmc/host/mtk-sd.c b/drivers/mmc/host/mtk-sd.c
> > index edade0e54a0c..483353ea3a99 100644
> > --- a/drivers/mmc/host/mtk-sd.c
> > +++ b/drivers/mmc/host/mtk-sd.c
> > @@ -2453,6 +2453,7 @@ static void msdc_hs400_enhanced_strobe(struct
> > mmc_host *mmc,
> >  static void msdc_cqe_enable(struct mmc_host *mmc)
> >  {
> >         struct msdc_host *host = mmc_priv(mmc);
> > +       struct cqhci_host *cq_host = mmc->cqe_private;
> > 
> >         /* enable cmdq irq */
> >         writel(MSDC_INT_CMDQ, host->base + MSDC_INTEN);
> > @@ -2462,6 +2463,8 @@ static void msdc_cqe_enable(struct mmc_host
> > *mmc)
> >         msdc_set_busy_timeout(host, 20 * 1000000000ULL, 0);
> >         /* default read data timeout 1s */
> >         msdc_set_timeout(host, 1000000000ULL, 0);
> > +
> > +       cqhci_writel(cq_host, 0x40, CQHCI_SSC1);
> >  }
> > 
> >  static void msdc_cqe_disable(struct mmc_host *mmc, bool recovery)
> > --
> > 2.25.1
> >