From: Marek Vasut <marex@denx.de>
To: Raviteja Narayanam <rna@xilinx.com>,
"linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org>,
Michal Simek <michals@xilinx.com>
Cc: "linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
git <git@xilinx.com>
Subject: Re: [PATCH 02/10] i2c: xiic: Add standard mode support for > 255 byte read transfers
Date: Thu, 3 Jun 2021 11:57:20 +0200 [thread overview]
Message-ID: <df5d8f33-1fe0-5760-b19d-300c1f99344e@denx.de> (raw)
In-Reply-To: <SN6PR02MB4093F1992FA306C027D01448CA3C9@SN6PR02MB4093.namprd02.prod.outlook.com>
On 6/3/21 7:33 AM, Raviteja Narayanam wrote:
[...]
>>> + if (i2c->dynamic) {
>>> + u8 bytes;
>>> + u16 val;
>>> +
>>> + /* Clear and enable Rx full interrupt. */
>>> + xiic_irq_clr_en(i2c, XIIC_INTR_RX_FULL_MASK |
>>> + XIIC_INTR_TX_ERROR_MASK);
>>> +
>>> + /*
>>> + * We want to get all but last byte, because the TX_ERROR
>> IRQ
>>> + * is used to indicate error ACK on the address, and
>>> + * negative ack on the last received byte, so to not mix
>>> + * them receive all but last.
>>> + * In the case where there is only one byte to receive
>>> + * we can check if ERROR and RX full is set at the same time
>>> + */
>>> + rx_watermark = msg->len;
>>> + bytes = min_t(u8, rx_watermark, IIC_RX_FIFO_DEPTH);
>>> + bytes--;
>>> +
>>> + xiic_setreg8(i2c, XIIC_RFD_REG_OFFSET, bytes);
>>> +
>>> + local_irq_save(flags);
>>> + if (!(msg->flags & I2C_M_NOSTART))
>>> + /* write the address */
>>> + xiic_setreg16(i2c, XIIC_DTR_REG_OFFSET,
>>> + i2c_8bit_addr_from_msg(msg) |
>>> + XIIC_TX_DYN_START_MASK);
>>> +
>>> + xiic_irq_clr_en(i2c, XIIC_INTR_BNB_MASK);
>>> +
>>> + /* If last message, include dynamic stop bit with length */
>>> + val = (i2c->nmsgs == 1) ? XIIC_TX_DYN_STOP_MASK : 0;
>>> + val |= msg->len;
>>> +
>>> + xiic_setreg16(i2c, XIIC_DTR_REG_OFFSET, val);
>>> + local_irq_restore(flags);
>>
>> Is local_irq_save()/local_irq_restore() used here to prevent concurrent
>> access to the XIIC ?
>
> These were used to fix the timing constraint between two register writes to the IP.
> As we have discussed last time, these are removed in " [PATCH 08/10] i2c: xiic: Remove interrupt enable/disable in Rx path".
> Now they are no longer needed since our IP is fixed.
> For legacy IP versions, driver is switching to 'AXI I2C standard mode' of operation in
> " [PATCH 07/10] i2c: xiic: Switch to Xiic standard mode for i2c-read".
I see, I would expect such fixes to be at the beginning of the series,
so they can be picked into linux-stable.
In fact, now that you mention the bugfixes which I posted a year ago,
they also fixed a multitude of locking issues on SMP in the xiic driver.
Has this series been tested on SMP Zynq or ZynqMP extensively ?
next prev parent reply other threads:[~2021-06-03 9:57 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-31 13:19 [PATCH 00/10] i2c: xiic: Add features, bug fixes Raviteja Narayanam
2021-05-31 13:19 ` [PATCH 01/10] i2c: xiic: Fix Tx Interrupt path for grouped messages Raviteja Narayanam
2021-05-31 13:19 ` [PATCH 02/10] i2c: xiic: Add standard mode support for > 255 byte read transfers Raviteja Narayanam
2021-06-02 11:17 ` Marek Vasut
2021-06-03 5:33 ` Raviteja Narayanam
2021-06-03 9:57 ` Marek Vasut [this message]
2021-06-08 9:46 ` Raviteja Narayanam
2021-05-31 13:19 ` [PATCH 03/10] i2c: xiic: Fix coding style issues Raviteja Narayanam
2021-05-31 15:49 ` Joe Perches
2021-05-31 13:19 ` [PATCH 04/10] i2c: xiic: Add smbus_block_read functionality Raviteja Narayanam
2021-05-31 13:19 ` [PATCH 05/10] i2c: xiic: Return value of xiic_reinit Raviteja Narayanam
2021-05-31 13:19 ` [PATCH 06/10] i2c: xiic: Fix the type check for xiic_wakeup Raviteja Narayanam
2021-05-31 13:19 ` [PATCH 07/10] i2c: xiic: Switch to Xiic standard mode for i2c-read Raviteja Narayanam
2021-05-31 13:19 ` [PATCH 08/10] i2c: xiic: Remove interrupt enable/disable in Rx path Raviteja Narayanam
2021-05-31 13:19 ` [PATCH 09/10] dt-bindings: i2c: xiic: Add 'xlnx,axi-iic-2.1' to compatible Raviteja Narayanam
2021-05-31 13:19 ` [PATCH 10/10] i2c: xiic: Update compatible with new IP version Raviteja Narayanam
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