Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.31 as permitted sender) client-ip=23.128.96.31;
Message-ID: <4999b3d9-e299-6c0b-0a08-11b33d06a636@amperemail.onmicrosoft.com>
Date:   Mon, 16 Oct 2023 09:52:17 +0700
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101
 Thunderbird/102.15.1
Subject: Re: [PATCH v1] i2c: designware: Disable TX_EMPTY irq while waiting
 for block length byte
Content-Language: en-US
To:     Yann Sionneau <ysionneau@kalrayinc.com>,
        Tam Nguyen <tamnguyenchi@os.amperecomputing.com>,
        linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org
Cc:     patches@amperecomputing.com, jarkko.nikula@linux.intel.com,
        andriy.shevchenko@linux.intel.com, mika.westerberg@linux.intel.com,
        jsd@semihalf.com, chuong@os.amperecomputing.com,
        darren@os.amperecomputing.com, stable@vger.kernel.org
References: <20230929035356.6435-1-tamnguyenchi@os.amperecomputing.com>
 <9e737b85-95bb-66cd-301c-3a2d1d41f4c8@kalrayinc.com>
From:   Tam Chi Nguyen <tamnguyenchi@amperemail.onmicrosoft.com>
In-Reply-To: <9e737b85-95bb-66cd-301c-3a2d1d41f4c8@kalrayinc.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?N0FCVW5FSUFaRjl5VWhJWGpYdWs5OEZqZUVod29UM0N1WmgvNlB5MmtYT1N1?=
 =?utf-8?B?dExDbURiMnUxUWpoVW5YR2lNelB3d08wMnI0MGk2ZldrTW9LTUVkZjdEZnRv?=
 =?utf-8?B?Qm5ST1FCc0ZzMitnSVRLb3luc0hnUXBhc1hmRytmNm1lSzN1UjltdC9RbmFV?=
 =?utf-8?B?TndIaHdKd3hEQUpwZVdrVVhQeWxFM0FNdk1hUzdSRy9pSm0yOUpDc2NtNFVD?=
 =?utf-8?B?WExLaU1uRzhsM0RRTWEvN0tmMWdSMDg1WkhoalExdmNtbjRxQUNYNGtuL0NZ?=
 =?utf-8?B?SHRnUS9hbjNuZHZuR3B0UDNlejhXSVU1a1ljc2FDbDRyM0dzVWhqazF6ckdj?=
 =?utf-8?B?UmtUZmxQcno2UjV0ajJGL2dkZ1Q3em1BbmJndFB4cVVhRStRckpmajNHb2JN?=
 =?utf-8?B?QVNINWc2OUcxbGUvQVRSRFNhUjM2dUpPTFdiQmUydnh1dlhGc0g0elA1VjVJ?=
 =?utf-8?B?emVYSmh5NUMxZ0k1MytvNFVkK25FWjdGY2llbFc0aUR6WFp4cVJBSXR4dy9Q?=
 =?utf-8?B?M0R2bjUxQWNqcGhjOFZuWTBUaXZxeUY3ajBxeVBnNXFsK1psV0pWdkJWQVpL?=
 =?utf-8?B?WTRWTnBkTVlHTTUwMDNKeS81WmFERHBYZ25Ub2ZoM05sdFJ5UHBubW1wKzhu?=
 =?utf-8?B?dkRXNFBOekpUOUNpWDBqOEpDbjJOSVRIT0xXK1llSzFIcTFMMXJSNmRRMGdV?=
 =?utf-8?B?SUZyRmpxQXk3UmZuSkNXd0hycHZkdVhKRU9RNEUrUWpza3JCM3V0TXY0RG9C?=
 =?utf-8?B?UVNDTG9jeEVrUnJ4bmNzWjQ2S0JzR2hneENEOWs2V1RiMkRBZC8wT1lOQkF0?=
 =?utf-8?B?V1FDTkhmMHd5Vkl5Y3RBbG1ha3k3WE1Cd2s2ZUw5Q0lkKytzSFdnZkZNWU5G?=
 =?utf-8?B?MWtPVXlFeVloY3NycW9BczFueUo5QWNGaGl1U2paLzJycGtPQUhHZENKdWM3?=
 =?utf-8?B?ZnZSRSs0NXp4K0JNVFBEMTExaklLTDQ1cHFLSjl4UkZjN2FPM2NsTUFJd3Vw?=
 =?utf-8?B?aStaeUloeElhdFJUaTZ5SEE2R0RIeVdOdU9iNEp6QWRXOXpnL1Q1cjRUa2pY?=
 =?utf-8?B?QmFmemhma05LY1BDaExQeGwzVTZmYThDeW5La0hIQzU0QlhNNjZ1SC9JaEpB?=
 =?utf-8?B?Y0ltU1pUWjhBQjhxMVdIWjFQOWlwUWQvRFZUSFJTS3V4ZElHT1Jzc1dBU2lQ?=
 =?utf-8?B?K2hzTVo4SGc3SmUrVmxYT0FZOG4wK0R5b3RJTzlZcTQrb3g3R1NlZzIzMVVC?=
 =?utf-8?B?bGQ2VEZVUmJiYTFJWS9NWlMzOGV2L2NqNmJRVFYyczFlVkRTUkQ2dk83SjNk?=
 =?utf-8?B?MjQ0azUwMVlPaitqT3NrWlF1RllaMVZGSmxIQzdaUE5JbGpaS0FwWEV3aHgr?=
 =?utf-8?B?Q1RWNW9xb1VzemFrUWx6UUxsMFZ5ZDE5SXI5V0pUa2wyYlVFNlk4VDFubGlt?=
 =?utf-8?B?V1NtNlJRWHhiZ3NDQnI5eUJ1dFE3Zk9zUHRwdTlSRUxIb0Z0NmtTV0VMdXNp?=
 =?utf-8?B?bHJEK0xRVFgzV2pCV2ZMcGdOaC9aZGF2bTd1LzJ5MHU4bzI4UXRzczRETEhq?=
 =?utf-8?B?ZFVIdDZHQzhHZ1AwTW44TXdnVTkwME9pVlg5elh1T3VHczdEZFNPVzd0ZTV1?=
 =?utf-8?B?cnE3N0w4N1oxeFJjWU5tZFdqZjBZaHdHVEt4ZUt0bXFvRm9ob3VQdVh2S2pR?=
 =?utf-8?B?aTNZaGhpbWQ1aUNsSy9TZ1Y3ZWlsbm1LUHVmazEwWTkxZkVuMDNzT0tqajBr?=
 =?utf-8?B?UnZDQWhtZVdpOS9KZzZvbmJ6NFBIbEo1U0cwa1d3WFJXd2p2SHFza2dXQjdo?=
 =?utf-8?B?U3pSOWVtZ0RUNGVUNCtEZ2xKVmhhNUVRSW9SMWwxWWs1dWNrWnNNNVdsU1Bs?=
 =?utf-8?B?VncyNk5CWGw1eGptZjk0a2NSa0VJR0o0MSs4Wk9tWkpnUEtJNkVBRERpNE1l?=
 =?utf-8?B?SGNoMGJGZUY3WFdGc2tNOGdwdkdsbkF2ellRMEV4UDVmWTFCQkdNK21Qbm05?=
 =?utf-8?B?MjhuL2RFOUFjdXlJRzlHdkRBYzVWUEhWcktyU0FWMGZmWnJhelhhR1c2VjFp?=
 =?utf-8?B?T0JNaHpQa2JuQVY0OW01Zm41RzBMT2hkeUVYUnJCeStSTWxLUHo5WVIwOXVV?=
 =?utf-8?B?bnFHa1N6K1luc0RVYm52VnRzNzZYUXVvU21kRnZPbGdUdmN1ZnNPUnJiYklW?=
 =?utf-8?Q?rpe9xIC3wYjHORiyMuRsR3w96YsInyn8dS7GUs3AdeC/?=
X-OriginatorOrg: amperemail.onmicrosoft.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 17373cfb-83ae-42f1-f115-08dbcdf2f002
X-MS-Exchange-CrossTenant-AuthSource: SA1PR01MB8131.prod.exchangelabs.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 16 Oct 2023 02:52:29.6768
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 3bc2b170-fd94-476d-b0ce-4229bdc904a7
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: 8SJjf0lwiqmaRis2dAnsFfWXVi5D1qOZX71YUuN0mSluVxVV1wk8CVdzGdDihAdyp4bPuVZOyb53ty28Jhoe371/oCUzNzkDBq2lp6algV/AQw74Id+RgKY4ea8eUrFf
X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH0PR01MB7049
X-Spam-Status: No, score=-3.6 required=5.0 tests=DKIM_INVALID,DKIM_SIGNED,
	FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,
	MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS
	autolearn=unavailable autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on morse.vger.email
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (morse.vger.email [0.0.0.0]); Sun, 15 Oct 2023 19:52:44 -0700 (PDT)


On 10/3/2023 15:11, Yann Sionneau wrote:
> Hi Tam,
>
> On 9/29/23 05:53, Tam Nguyen wrote:
>> During SMBus block data read process, we have seen high interrupt rate
>> because of TX_EMPTY irq status while waiting for block length byte (the
>> first data byte after the address phase). The interrupt handler does not
>> do anything because the internal state is kept as 
>> STATUS_WRITE_IN_PROGRESS.
>> Hence, we should disable TX_EMPTY irq until I2C DW receives first data
>> byte from I2C device, then re-enable it.
>>
>> It takes 0.789 ms for host to receive data length from slave.
>> Without the patch, i2c_dw_isr is called 99 times by TX_EMPTY interrupt.
>> And it is none after applying the patch.
>>
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Chuong Tran <chuong@os.amperecomputing.com>
>> Signed-off-by: Tam Nguyen <tamnguyenchi@os.amperecomputing.com>
>> ---
>>   drivers/i2c/busses/i2c-designware-master.c | 13 +++++++++++++
>>   1 file changed, 13 insertions(+)
>>
>> diff --git a/drivers/i2c/busses/i2c-designware-master.c 
>> b/drivers/i2c/busses/i2c-designware-master.c
>> index 55ea91a63382..2152b1f9b27c 100644
>> --- a/drivers/i2c/busses/i2c-designware-master.c
>> +++ b/drivers/i2c/busses/i2c-designware-master.c
>> @@ -462,6 +462,13 @@ i2c_dw_xfer_msg(struct dw_i2c_dev *dev)
>>           if (buf_len > 0 || flags & I2C_M_RECV_LEN) {
>>               /* more bytes to be written */
>>               dev->status |= STATUS_WRITE_IN_PROGRESS;
>> +            /*
>> +             * In I2C_FUNC_SMBUS_BLOCK_DATA case, there is no data
>> +             * to send before receiving data length from slave.
>> +             * Disable TX_EMPTY while waiting for data length byte
>> +             */
>> +            if (flags & I2C_M_RECV_LEN)
>> +                intr_mask &= ~DW_IC_INTR_TX_EMPTY;
>>               break;
>>           } else
>>               dev->status &= ~STATUS_WRITE_IN_PROGRESS;
>> @@ -485,6 +492,7 @@ i2c_dw_recv_len(struct dw_i2c_dev *dev, u8 len)
>>   {
>>       struct i2c_msg *msgs = dev->msgs;
>>       u32 flags = msgs[dev->msg_read_idx].flags;
>> +    u32 intr_mask;
>>         /*
>>        * Adjust the buffer length and mask the flag
>> @@ -495,6 +503,11 @@ i2c_dw_recv_len(struct dw_i2c_dev *dev, u8 len)
>>       msgs[dev->msg_read_idx].len = len;
>>       msgs[dev->msg_read_idx].flags &= ~I2C_M_RECV_LEN;
>>   +    /* Re-enable TX_EMPTY interrupt. */
>> +    regmap_read(dev->map, DW_IC_INTR_MASK, &intr_mask);
>> +    intr_mask |= DW_IC_INTR_TX_EMPTY;
>> +    regmap_write(dev->map, DW_IC_INTR_MASK, intr_mask);
>> +
>>       return len;
>>   }
>
> I tested this patch on Kalray k200 and k200lp boards (Coolidge SoC, 
> kvx arch). With this patch all our CI pipelines are green.
>
Thank you for your time to test this patch.

> Tested-by: Yann Sionneau <ysionneau@kalrayinc.com>
>