Re: [PATCH v3 5/6] spi: at91-usart: add driver for at91-usart as spi

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On 05/17/2018 08:04 AM, Mark Brown wrote:
On Fri, May 11, 2018 at 01:38:21PM +0300, Radu Pirea wrote:

+config SPI_AT91_USART
+        tristate "Atmel USART Controller as SPI"
+	depends on HAS_DMA
+	depends on (ARCH_AT91 || COMPILE_TEST)
+        select MFD_AT91_USART
+	help
+	  This selects a driver for the AT91 USART Controller as SPI Master,
+	  present on AT91 and SAMA5 SoC series.
+

This looks like there's some tab/space mixing going on here.

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for AT91 USART Controllers as SPI
+ *
+ * Copyright (C) 2018 Microchip Technology Inc.

Make the entire block a C++ comment so it looks more intentional rather
tha mixing C and C++.

Hi Mark,

I know it's ugly, but SPDX license identifier must be in a separate comment block.


+static inline void at91_usart_spi_tx(struct at91_usart_spi *aus)
+{
+	unsigned int len = aus->current_transfer->len;
+	unsigned int remaining = aus->current_tx_remaining_bytes;
+	const u8  *tx_buf = aus->current_transfer->tx_buf;
+
+	if (tx_buf && remaining) {
+		if (at91_usart_spi_tx_ready(aus))
+			spi_writel(aus, THR, tx_buf[len - remaining]);
+			aus->current_tx_remaining_bytes--;

Missing braces here - we only write to the FIFO if there's space but we
unconditionally decrement the counter.


Thanks. I will fix it.

+	} else {
+		if (at91_usart_spi_tx_ready(aus))
+			spi_writel(aus, THR, US_DUMMY_TX);
+	}
+}

This looks like you're open coding SPI_CONTROLLER_MUST_TX

+	int len = aus->current_transfer->len;
+	int remaining = aus->current_rx_remaining_bytes;
+	u8  *rx_buf = aus->current_transfer->rx_buf;
+
+	if (aus->current_rx_remaining_bytes) {
+		rx_buf[len - remaining] = spi_readb(aus, RHR);
+		aus->current_rx_remaining_bytes--;
+	} else {
+		spi_readb(aus, RHR);
+	}

Similarly for _MUST_RX.

+	controller->flags = SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX;

You're actually setting both flags...  this means that the handling for
cases with missing TX or RX buffers can't happen.

Sorry. My mistake. I will remove unnecessary code.
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