linux-kernel - Re: [PATCH 2/2] i2c: designware: enable High-speed mode for pcidrv

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Date:	Mon, 12 Oct 2015 15:41:01 +0800
From:	Xiang Wang <wangxfdu@...il.com>
To:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:	xiang.a.wang@...el.com, wsa@...-dreams.de,
	jarkko.nikula@...ux.intel.com, linux-i2c@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] i2c: designware: enable High-speed mode for pcidrv

Hi, Andy
Thanks for your comments.

[Andy] Don't see a relationship between PCI driver and this ACPI stuff.
Although this is a pci driver, we may enumerate the i2c devices from
DSDT table while i2c controllers are enumerated via PCI. In this
scenario, in DSDT, there are descriptions of i2c devices as well as
i2c controllers. The ACPI node of i2c controllers are bond to i2c PCI
devices via pci-acpi glue.
So if we want to determine the i2c devices' settings (e.g. bus speed),
we should leverage ACPI.

Above is also the reason why the ACPI stuff is put in
i2c-designware-core: i2c_dw_acpi_setup_speed can be used by both plat
and pci driver. Thanks

2015-10-09 17:31 GMT+08:00 Andy Shevchenko <andriy.shevchenko@...ux.intel.com>:
> On Fri, 2015-10-09 at 16:47 +0800, wangxfdu@...il.com wrote:
>> From: Xiang Wang <xiang.a.wang@...el.com>
>>
>> 1. Support setting hs_hcnt and hs_lcnt
>> 2. Get bus speed mode from ACPI companion of the
>> i2c controller.
>>
>> Signed-off-by: Xiang Wang <xiang.a.wang@...el.com>
>> ---
>>  drivers/i2c/busses/i2c-designware-pcidrv.c | 7 +++++++
>>  1 file changed, 7 insertions(+)
>>
>> diff --git a/drivers/i2c/busses/i2c-designware-pcidrv.c
>> b/drivers/i2c/busses/i2c-designware-pcidrv.c
>> index 6643d2d..0f4c0c4 100644
>> --- a/drivers/i2c/busses/i2c-designware-pcidrv.c
>> +++ b/drivers/i2c/busses/i2c-designware-pcidrv.c
>> @@ -54,8 +54,10 @@ enum dw_pci_ctl_id_t {
>>  struct dw_scl_sda_cfg {
>>       u32 ss_hcnt;
>>       u32 fs_hcnt;
>> +     u32 hs_hcnt;
>>       u32 ss_lcnt;
>>       u32 fs_lcnt;
>> +     u32 hs_lcnt;
>>       u32 sda_hold;
>>  };
>>
>> @@ -237,8 +239,10 @@ static int i2c_dw_pci_probe(struct pci_dev
>> *pdev,
>>               cfg = controller->scl_sda_cfg;
>>               dev->ss_hcnt = cfg->ss_hcnt;
>>               dev->fs_hcnt = cfg->fs_hcnt;
>> +             dev->hs_hcnt = cfg->hs_hcnt;
>>               dev->ss_lcnt = cfg->ss_lcnt;
>>               dev->fs_lcnt = cfg->fs_lcnt;
>> +             dev->hs_lcnt = cfg->hs_lcnt;
>>               dev->sda_hold_time = cfg->sda_hold;
>>       }
>>
>> @@ -246,6 +250,9 @@ static int i2c_dw_pci_probe(struct pci_dev *pdev,
>>
>>       dev->tx_fifo_depth = controller->tx_fifo_depth;
>>       dev->rx_fifo_depth = controller->rx_fifo_depth;
>> +
>> +     i2c_dw_acpi_setup_speed(&pdev->dev, dev);
>
> Don't see a relationship between PCI driver and this ACPI stuff.
>
>> +
>>       r = i2c_dw_init(dev);
>>       if (r)
>>               return r;
>
> --
> Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> Intel Finland Oy



-- 
Regards,
Xiang
--
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