linux-kernel - Re: [PATCH 28/40] Input: atmel_mxt_ts - Add CHG line handling in bootloader code

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Date:	Fri, 22 Feb 2013 14:35:03 -0800
From:	Benson Leung <bleung@...omium.org>
To:	Nick Dyer <nick.dyer@...ev.co.uk>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Daniel Kurtz <djkurtz@...omium.org>,
	Henrik Rydberg <rydberg@...omail.se>,
	Joonyoung Shim <jy0922.shim@...sung.com>,
	"Bowens, Alan" <Alan.Bowens@...el.com>,
	linux-input@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Peter Meerwald <pmeerw@...erw.net>,
	Olof Johansson <olofj@...omium.org>,
	Yufeng Shen <miletus@...omium.org>
Subject: Re: [PATCH 28/40] Input: atmel_mxt_ts - Add CHG line handling in
 bootloader code

This is very similar to a patch that Daniel and I sent earlier this month.

http://www.spinics.net/lists/linux-input/msg24666.html

The major difference is that your wait_for_chg does a polling read of
chg, while the one we worked on leaves the irq enabled and waits on
completion.

On Fri, Feb 22, 2013 at 9:58 AM, Nick Dyer <nick.dyer@...ev.co.uk> wrote:
> The bootloader state machine toggles the CHG/Interrupt line to indicate when
> it has transitioned between states. Waiting for this event improves bootloader
> reliability.
>
> Signed-off-by: Nick Dyer <nick.dyer@...ev.co.uk>
> ---
>  drivers/input/touchscreen/atmel_mxt_ts.c |   29 +++++++++++++++++++++++++++--
>  1 file changed, 27 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
> index a1f196b..f182228 100644
> --- a/drivers/input/touchscreen/atmel_mxt_ts.c
> +++ b/drivers/input/touchscreen/atmel_mxt_ts.c
> @@ -430,6 +430,27 @@ static int mxt_probe_bootloader(struct mxt_data *data)
>         return 0;
>  }
>
> +static int mxt_wait_for_chg(struct mxt_data *data)
> +{
> +       int timeout_counter = 0;
> +       int count = 1E6;
> +
> +       if (data->pdata->read_chg == NULL) {
> +               msleep(20);
> +               return 0;
> +       }
> +
> +       while ((timeout_counter++ <= count) && data->pdata->read_chg())
> +               udelay(20);
> +
> +       if (timeout_counter > count) {
> +               dev_err(&data->client->dev, "mxt_wait_for_chg() timeout!\n");
> +               return -EIO;
> +       }
> +
> +       return 0;
> +}
> +
>  static u8 mxt_get_bootloader_version(struct mxt_data *data, u8 val)
>  {
>         struct device *dev = &data->client->dev;
> @@ -478,9 +499,10 @@ recheck:
>                 val &= ~MXT_BOOT_STATUS_MASK;
>                 break;
>         case MXT_FRAME_CRC_PASS:
> -               if (val == MXT_FRAME_CRC_CHECK)
> +               if (val == MXT_FRAME_CRC_CHECK) {
> +                       mxt_wait_for_chg(data);
>                         goto recheck;
> -               if (val == MXT_FRAME_CRC_FAIL) {
> +               } else if (val == MXT_FRAME_CRC_FAIL) {
>                         dev_err(dev, "Bootloader CRC fail\n");
>                         return -EINVAL;
>                 }
> @@ -1781,6 +1803,7 @@ static int mxt_load_fw(struct device *dev, const char *fn)
>
>         ret = mxt_check_bootloader(data, MXT_WAITING_BOOTLOAD_CMD);
>         if (ret) {
> +               mxt_wait_for_chg(data);
>                 /* Bootloader may still be unlocked from previous update
>                  * attempt */
>                 ret = mxt_check_bootloader(data, MXT_WAITING_FRAME_DATA);
> @@ -1800,6 +1823,7 @@ static int mxt_load_fw(struct device *dev, const char *fn)
>         }
>
>         while (pos < fw->size) {
> +               mxt_wait_for_chg(data);
>                 ret = mxt_check_bootloader(data, MXT_WAITING_FRAME_DATA);
>                 if (ret) {
>                         data->state = FAILED;
> @@ -1818,6 +1842,7 @@ static int mxt_load_fw(struct device *dev, const char *fn)
>                         goto release_firmware;
>                 }
>
> +               mxt_wait_for_chg(data);
>                 ret = mxt_check_bootloader(data, MXT_FRAME_CRC_PASS);
>                 if (ret) {
>                         retry++;
> --
> 1.7.10.4
>



--
Benson Leung
Software Engineer, Chrom* OS
bleung@...omium.org
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