Messages in this thread | | | Subject | Re: [PATCH 02/10] i2c: xiic: Add standard mode support for > 255 byte read transfers | From | Marek Vasut <> | Date | Thu, 3 Jun 2021 11:57:20 +0200 |
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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 ?
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