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List:       linux-mmc
Subject:    Re: [PATCH v2 5/5] mmc: dw: Add fifo watermark quirk
From:       Jaehoon Chung <jh80.chung () samsung ! com>
Date:       2016-10-31 9:35:04
Message-ID: db1f0415-41a0-8a94-b2fb-bfc39b3cee2a () samsung ! com
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On 10/31/2016 05:48 PM, Jun Nie wrote:
> 2016-10-28 13:30 GMT+08:00 Jaehoon Chung <jh80.chung@samsung.com>:
>> On 10/28/2016 11:37 AM, Jun Nie wrote:
>>> Data done irq is expected if data length is less than
>>> watermark in PIO mode. But fifo watermark is requested
>>> to be aligned with data length in some SoC so that TX/RX
>>> irq can be generated with data done irq. Add the
>>> watermark quirk to mark this requirement and force
>>> fifo watermark setting accordingly.
>>>
>>> Signed-off-by: Jun Nie <jun.nie@linaro.org>
>>> ---
>>>  drivers/mmc/host/dw_mmc.c  | 11 +++++++++--
>>>  include/linux/mmc/dw_mmc.h |  2 ++
>>>  2 files changed, 11 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
>>> index 24ae05b6..e0f49cc 100644
>>> --- a/drivers/mmc/host/dw_mmc.c
>>> +++ b/drivers/mmc/host/dw_mmc.c
>>> @@ -1111,11 +1111,15 @@ static void dw_mci_submit_data(struct dw_mci *host, struct mmc_data *data)
>>>               mci_writel(host, CTRL, temp);
>>>
>>>               /*
>>> -              * Use the initial fifoth_val for PIO mode.
>>> +              * Use the initial fifoth_val for PIO mode. If wm_quirk
>>> +              * is set, we set watermark same as data size.
>>>                * If next issued data may be transfered by DMA mode,
>>>                * prev_blksz should be invalidated.
>>>                */
>>> -             mci_writel(host, FIFOTH, host->fifoth_val);
>>> +             if (host->wm_quirk)
>>> +                     dw_mci_adjust_fifoth(host, data);
>>> +             else
>>> +                     mci_writel(host, FIFOTH, host->fifoth_val);
>>>               host->prev_blksz = 0;
>>>       } else {
>>>               /*
>>> @@ -2957,6 +2961,9 @@ static struct dw_mci_board *dw_mci_parse_dt(struct dw_mci *host)
>>>
>>>       of_property_read_u32(np, "fifo-addr", &host->fifo_addr_override);
>>>
>>> +     if (of_get_property(np, "fifo-watermark-quirk", NULL))
>>> +             host->wm_quirk = true;
>>> +
>>>       if (!of_property_read_u32(np, "clock-frequency", &clock_frequency))
>>>               pdata->bus_hz = clock_frequency;
>>>
>>> diff --git a/include/linux/mmc/dw_mmc.h b/include/linux/mmc/dw_mmc.h
>>> index 4866ef5..2ccfd9c 100644
>>> --- a/include/linux/mmc/dw_mmc.h
>>> +++ b/include/linux/mmc/dw_mmc.h
>>> @@ -108,6 +108,7 @@ struct dw_mci_dma_slave {
>>>   * @slot: Slots sharing this MMC controller.
>>>   * @fifo_depth: depth of FIFO.
>>>   * @fifo_addr_override: override fifo reg offset with this value.
>>> + * @wm_quirk: force fifo watermark equal with data length in PIO mode.
>>
>> quirk...hmm..It might be just my preference..
>> quirk looks like workaround...so how about changing other name?
> 
> How about fifo_wm_aligned ?

If it's not quirk or workaround, whatever. :)

Best Regards,
Jaehoon Chung

> 
>>
>>>   * @data_shift: log2 of FIFO item size.
>>>   * @part_buf_start: Start index in part_buf.
>>>   * @part_buf_count: Bytes of partial data in part_buf.
>>> @@ -156,6 +157,7 @@ struct dw_mci {
>>>       void __iomem            *regs;
>>>       void __iomem            *fifo_reg;
>>>       u32                     fifo_addr_override;
>>> +     u32                     wm_quirk;
>>
>> For True or false, u32?
> True means alignment is needed. Will add  this to comments.
>>
>>>
>>>       struct scatterlist      *sg;
>>>       struct sg_mapping_iter  sg_miter;
>>>
>>
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> 

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