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References: <20190114095804.27978-1-hch@lst.de> <20190114095804.27978-8-hch@lst.de>
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From:   Ulf Hansson <ulf.hansson@linaro.org>
Date:   Wed, 30 Jan 2019 08:55:07 +0100
Message-ID: <CAPDyKFrtJmaS33=yZz7ubUVVb5UB-Euq5pcaBMSFeQyubDYvGA@mail.gmail.com>
Subject: Re: [PATCH 07/11] mmc: mvsdio: handle highmem pages
To:     Christoph Hellwig <hch@lst.de>
Cc:     Russell King <linux@armlinux.org.uk>,
        Nicolas Pitre <nico@fluxnic.net>,
        Aaro Koskinen <aaro.koskinen@iki.fi>,
        Ben Dooks <ben-linux@fluff.org>,
        "linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        linux-omap <linux-omap@vger.kernel.org>,
        "list@263.net:IOMMU DRIVERS <iommu@lists.linux-foundation.org>, Joerg
        Roedel <joro@8bytes.org>," <iommu@lists.linux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon, 14 Jan 2019 at 10:58, Christoph Hellwig <hch@lst.de> wrote:
>
> Instead of setting up a kernel pointer to track the current PIO address,
> track the offset in the current page, and do an atomic kmap for the page
> while doing the actual PIO operations.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  drivers/mmc/host/mvsdio.c | 48 +++++++++++++++++++++++----------------
>  1 file changed, 29 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/mmc/host/mvsdio.c b/drivers/mmc/host/mvsdio.c
> index e22bbff89c8d..545e370d6dae 100644
> --- a/drivers/mmc/host/mvsdio.c
> +++ b/drivers/mmc/host/mvsdio.c
> @@ -12,6 +12,7 @@
>  #include <linux/module.h>
>  #include <linux/init.h>
>  #include <linux/io.h>
> +#include <linux/highmem.h>
>  #include <linux/platform_device.h>
>  #include <linux/mbus.h>
>  #include <linux/delay.h>
> @@ -42,7 +43,8 @@ struct mvsd_host {
>         unsigned int intr_en;
>         unsigned int ctrl;
>         unsigned int pio_size;
> -       void *pio_ptr;
> +       struct scatterlist *pio_sg;
> +       unsigned int pio_offset; /* offset in words into the segment */
>         unsigned int sg_frags;
>         unsigned int ns_per_clk;
>         unsigned int clock;
> @@ -96,9 +98,9 @@ static int mvsd_setup_data(struct mvsd_host *host, struct mmc_data *data)
>         if (tmout_index > MVSD_HOST_CTRL_TMOUT_MAX)
>                 tmout_index = MVSD_HOST_CTRL_TMOUT_MAX;
>
> -       dev_dbg(host->dev, "data %s at 0x%08x: blocks=%d blksz=%d tmout=%u (%d)\n",
> +       dev_dbg(host->dev, "data %s at 0x%08llx: blocks=%d blksz=%d tmout=%u (%d)\n",
>                 (data->flags & MMC_DATA_READ) ? "read" : "write",
> -               (u32)sg_virt(data->sg), data->blocks, data->blksz,
> +               (u64)sg_phys(data->sg), data->blocks, data->blksz,
>                 tmout, tmout_index);
>
>         host->ctrl &= ~MVSD_HOST_CTRL_TMOUT_MASK;
> @@ -118,10 +120,11 @@ static int mvsd_setup_data(struct mvsd_host *host, struct mmc_data *data)
>                  * boundary.
>                  */
>                 host->pio_size = data->blocks * data->blksz;
> -               host->pio_ptr = sg_virt(data->sg);
> +               host->pio_sg = data->sg;
> +               host->pio_offset = data->sg->offset / 2;
>                 if (!nodma)
> -                       dev_dbg(host->dev, "fallback to PIO for data at 0x%p size %d\n",
> -                               host->pio_ptr, host->pio_size);
> +                       dev_dbg(host->dev, "fallback to PIO for data at 0x%x size %d\n",
> +                               host->pio_offset, host->pio_size);
>                 return 1;
>         } else {
>                 dma_addr_t phys_addr;
> @@ -291,8 +294,9 @@ static u32 mvsd_finish_data(struct mvsd_host *host, struct mmc_data *data,
>  {
>         void __iomem *iobase = host->base;
>
> -       if (host->pio_ptr) {
> -               host->pio_ptr = NULL;
> +       if (host->pio_sg) {
> +               host->pio_sg = NULL;
> +               host->pio_offset = 0;
>                 host->pio_size = 0;
>         } else {
>                 dma_unmap_sg(mmc_dev(host->mmc), data->sg, host->sg_frags,
> @@ -376,11 +380,12 @@ static irqreturn_t mvsd_irq(int irq, void *dev)
>         if (host->pio_size &&
>             (intr_status & host->intr_en &
>              (MVSD_NOR_RX_READY | MVSD_NOR_RX_FIFO_8W))) {
> -               u16 *p = host->pio_ptr;
> +               u16 *p = kmap_atomic(sg_page(host->pio_sg));

Seems like a corresponding kunmap_atomic() is missing somewhere.

> +               unsigned int o = host->pio_offset;
>                 int s = host->pio_size;
>                 while (s >= 32 && (intr_status & MVSD_NOR_RX_FIFO_8W)) {
> -                       readsw(iobase + MVSD_FIFO, p, 16);
> -                       p += 16;
> +                       readsw(iobase + MVSD_FIFO, p + o, 16);
> +                       o += 16;
>                         s -= 32;
>                         intr_status = mvsd_read(MVSD_NOR_INTR_STATUS);
>                 }
> @@ -391,8 +396,10 @@ static irqreturn_t mvsd_irq(int irq, void *dev)
>                  */
>                 if (s <= 32) {
>                         while (s >= 4 && (intr_status & MVSD_NOR_RX_READY)) {
> -                               put_unaligned(mvsd_read(MVSD_FIFO), p++);
> -                               put_unaligned(mvsd_read(MVSD_FIFO), p++);
> +                               put_unaligned(mvsd_read(MVSD_FIFO), p + o);
> +                               o++;
> +                               put_unaligned(mvsd_read(MVSD_FIFO), p + o);
> +                               o++;
>                                 s -= 4;
>                                 intr_status = mvsd_read(MVSD_NOR_INTR_STATUS);
>                         }
> @@ -400,7 +407,7 @@ static irqreturn_t mvsd_irq(int irq, void *dev)
>                                 u16 val[2] = {0, 0};
>                                 val[0] = mvsd_read(MVSD_FIFO);
>                                 val[1] = mvsd_read(MVSD_FIFO);
> -                               memcpy(p, ((void *)&val) + 4 - s, s);
> +                               memcpy(p + o, ((void *)&val) + 4 - s, s);
>                                 s = 0;
>                                 intr_status = mvsd_read(MVSD_NOR_INTR_STATUS);
>                         }
> @@ -416,13 +423,14 @@ static irqreturn_t mvsd_irq(int irq, void *dev)
>                 }
>                 dev_dbg(host->dev, "pio %d intr 0x%04x hw_state 0x%04x\n",
>                         s, intr_status, mvsd_read(MVSD_HW_STATE));
> -               host->pio_ptr = p;
> +               host->pio_offset = o;
>                 host->pio_size = s;
>                 irq_handled = 1;
>         } else if (host->pio_size &&
>                    (intr_status & host->intr_en &
>                     (MVSD_NOR_TX_AVAIL | MVSD_NOR_TX_FIFO_8W))) {
> -               u16 *p = host->pio_ptr;
> +               u16 *p = kmap_atomic(sg_page(host->pio_sg));

Ditto.

> +               unsigned int o = host->pio_offset;
>                 int s = host->pio_size;
>                 /*
>                  * The TX_FIFO_8W bit is unreliable. When set, bursting
> @@ -431,8 +439,10 @@ static irqreturn_t mvsd_irq(int irq, void *dev)
>                  * TX_FIFO_8W remains set.
>                  */
>                 while (s >= 4 && (intr_status & MVSD_NOR_TX_AVAIL)) {
> -                       mvsd_write(MVSD_FIFO, get_unaligned(p++));
> -                       mvsd_write(MVSD_FIFO, get_unaligned(p++));
> +                       mvsd_write(MVSD_FIFO, get_unaligned(p + o));
> +                       o++;
> +                       mvsd_write(MVSD_FIFO, get_unaligned(p + o));
> +                       o++;
>                         s -= 4;
>                         intr_status = mvsd_read(MVSD_NOR_INTR_STATUS);
>                 }
> @@ -453,7 +463,7 @@ static irqreturn_t mvsd_irq(int irq, void *dev)
>                 }
>                 dev_dbg(host->dev, "pio %d intr 0x%04x hw_state 0x%04x\n",
>                         s, intr_status, mvsd_read(MVSD_HW_STATE));
> -               host->pio_ptr = p;
> +               host->pio_offset = o;
>                 host->pio_size = s;
>                 irq_handled = 1;
>         }
> --
> 2.20.1
>

Kind regards
Uffe