Re: [PATCH 6/8] serial: Add Tegra Combined UART driver

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On 05/13/2018 06:36 PM, Jassi Brar wrote:
On Tue, May 8, 2018 at 5:14 PM, Mikko Perttunen <mperttunen@xxxxxxxxxx> wrote:

....

+config SERIAL_TEGRA_TCU
+       tristate "NVIDIA Tegra Combined UART"
+       depends on ARCH_TEGRA && MAILBOX
+       select SERIAL_CORE
+       help
+         Support for the mailbox-based TCU (Tegra Combined UART) serial port.
+         TCU is a virtual serial port that allows multiplexing multiple data
+         streams into a single hardware serial port.
+
Maybe make it depend upon TEGRA_HSP_MBOX ?

Yeah, that probably makes more sense. MAILBOX is enough to build it but it won't be of any use without TEGRA_HSP_MBOX.


......

+
+static void tegra_tcu_write(const char *s, unsigned int count)
+{
+       struct tegra_tcu *tcu = tegra_tcu_uart_port.private_data;
+       unsigned int written = 0, i = 0;
+       bool insert_nl = false;
+       uint32_t value = 0;
+
+       while (i < count) {
+               if (insert_nl) {
+                       value |= '\n' << (written++ * 8);
+                       insert_nl = false;
+                       i++;
+               } else if (s[i] == '\n') {
+                       value |= '\r' << (written++ * 8);
+                       insert_nl = true;
+               } else {
+                       value |= s[i++] << (written++ * 8);
+               }
+
+               if (written == 3) {
+                       value |= 3 << 24;
+                       value |= BIT(26);
+                       mbox_send_message(tcu->tx, &value);

How is this supposed to work? tegra_hsp_doorbell_send_data() ignores
the second argument.

The previous patch in the series adds support for what are called "shared mailboxes" to the tegra-hsp driver. For these the second argument is used.

Thanks,
Mikko

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