From: absahu@codeaurora•org (Abhishek Sahu)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 2/2] i2c: qup: Fixed the DMA segments length
Date: Wed, 11 May 2016 23:13:58 +0530 [thread overview]
Message-ID: <699f798ccc0a7d36640cef42ac26a697@codeaurora.org> (raw)
In-Reply-To: <000b01d1aba0$c2fea380$48fbea80$@codeaurora.org>
On 2016-05-11 21:48, Sricharan wrote:
> Hi,
>
>> 1. The current QCOM I2C driver code is failing for transfer length
>> greater
>> than 255. This is happening due to improper segments length as the I2C
>> DMA
>> segments can be maximum of 256 bytes.
>>
>> 2. The transfer length tlen was being initialized with 0 for 256
>> bytes,
>> which is
>> being passed for DMA mappings resulting in improper DMA mapping
>> length.
>>
>> This patch fixes the above said problems by initializing the block
>> count
>> with
>> the values calculated in qup_i2c_set_blk_data and calculating the
> remaining
>> length for last DMA segment. Also, the block data length need to be
>> decremented after each transfer. Additionally, this patch corrects the
>> tlen
>> assignment for DMA mapping.
>>
>> Signed-off-by: Abhishek Sahu <absahu@codeaurora•org>
>> ---
>> drivers/i2c/busses/i2c-qup.c | 12 +++++++-----
>> 1 file changed, 7 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-qup.c
>> b/drivers/i2c/busses/i2c-qup.c
>> index
>> 8c2f1bc..6d6b7dc 100644
>> --- a/drivers/i2c/busses/i2c-qup.c
>> +++ b/drivers/i2c/busses/i2c-qup.c
>> @@ -651,23 +651,24 @@ static int qup_i2c_bam_do_xfer(struct
>> qup_i2c_dev *qup, struct i2c_msg *msg,
>> u8 *tags;
>>
>> while (idx < num) {
>> - blocks = (msg->len + limit) / limit;
>> - rem = msg->len % limit;
>> tx_len = 0, len = 0, i = 0;
>>
>> qup->is_last = (idx == (num - 1));
>>
>> qup_i2c_set_blk_data(qup, msg);
>>
>> + blocks = qup->blk.count;
>> + rem = msg->len - (blocks - 1) * limit;
>> +
> Same if we had blocks = (msg->len + limit - 1) / limit instead of
> the
> above ?
Yes. We calculating this inside qup_i2c_set_blk_data and assigning the
same value to
qup->blk.count so I am using this to avoid redundant arithmetic
operations.
> Otherwise,
> Reviewed-by: Sricharan at codeaurora.org
>
> Regards,
> Sricharan
--
Abhishek Sahu
next prev parent reply other threads:[~2016-05-11 17:43 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-09 12:44 [PATCH 0/2] i2c: qup: Fixed the DMA transfer errors Abhishek Sahu
2016-05-09 12:44 ` [PATCH 1/2] i2c: qup: Cleared the error bits in ISR Abhishek Sahu
2016-05-11 15:57 ` Sricharan
2016-05-11 17:34 ` Abhishek Sahu
2016-05-12 2:28 ` Sricharan
2016-05-12 5:13 ` Andy Gross
2016-05-12 6:18 ` Abhishek Sahu
2016-05-12 17:58 ` Andy Gross
2016-05-12 19:32 ` Abhishek Sahu
2016-05-12 20:05 ` Andy Gross
2016-05-12 20:27 ` Abhishek Sahu
2016-06-18 16:32 ` Wolfram Sang
2016-06-20 12:48 ` Abhishek Sahu
2016-07-15 6:33 ` Wolfram Sang
2016-05-09 12:44 ` [PATCH 2/2] i2c: qup: Fixed the DMA segments length Abhishek Sahu
2016-05-11 16:18 ` Sricharan
2016-05-11 17:43 ` Abhishek Sahu [this message]
2016-07-15 6:38 ` Wolfram Sang
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