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Date:      Sun, 18 Jun 2017 21:03:35 +0000 (UTC)
From:      Warner Losh <imp@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r320080 - head/sys/arm/at91
Message-ID:  <201706182103.v5IL3Zh5049294@repo.freebsd.org>
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Author: imp
Date: Sun Jun 18 21:03:35 2017
New Revision: 320080
URL: https://svnweb.freebsd.org/changeset/base/320080

Log:
  Load the transmit dma buffer at attach time as well. We don't need to
  load and unload it all the time since the buffer never changes. In
  addition, we were loading it with a hardware spin lock held, which
  makes the sleepable lock in busdma (for the bounce pages) trigger a
  witness warning, as well as ipend being called with it held by uart,
  which made it impossible to unload.
  
  These differences don't matter with the v4 busdma implementation, but
  they do with the v6 implementation since the latter likes to bounce
  transactions more, and will always do so for Atmel's driver.
  
  It's more efficient as well as being more correct.

Modified:
  head/sys/arm/at91/uart_dev_at91usart.c

Modified: head/sys/arm/at91/uart_dev_at91usart.c
==============================================================================
--- head/sys/arm/at91/uart_dev_at91usart.c	Sun Jun 18 20:55:46 2017	(r320079)
+++ head/sys/arm/at91/uart_dev_at91usart.c	Sun Jun 18 21:03:35 2017	(r320080)
@@ -72,6 +72,7 @@ struct at91_usart_softc {
 	struct uart_softc base;
 	bus_dma_tag_t tx_tag;
 	bus_dmamap_t tx_map;
+	bus_addr_t tx_paddr;
 	uint32_t flags;
 #define	HAS_TIMEOUT		0x1
 #define	USE_RTS0_WORKAROUND	0x2
@@ -472,6 +473,9 @@ at91_usart_bus_attach(struct uart_softc *sc)
 	err = bus_dmamap_create(atsc->tx_tag, 0, &atsc->tx_map);
 	if (err != 0)
 		goto errout;
+	if (bus_dmamap_load(atsc->tx_tag, atsc->tx_map, sc->sc_txbuf,
+	    sc->sc_txfifosz, at91_getaddr, &atsc->tx_paddr, 0) != 0)
+		goto errout;
 
 	if (atsc->flags & HAS_TIMEOUT) {
 		/*
@@ -547,29 +551,22 @@ errout:
 static int
 at91_usart_bus_transmit(struct uart_softc *sc)
 {
-	bus_addr_t addr;
 	struct at91_usart_softc *atsc;
 	int err;
 
 	err = 0;
 	atsc = (struct at91_usart_softc *)sc;
 	uart_lock(sc->sc_hwmtx);
-	if (bus_dmamap_load(atsc->tx_tag, atsc->tx_map, sc->sc_txbuf,
-	    sc->sc_txdatasz, at91_getaddr, &addr, 0) != 0) {
-		err = EAGAIN;
-		goto errout;
-	}
 	bus_dmamap_sync(atsc->tx_tag, atsc->tx_map, BUS_DMASYNC_PREWRITE);
 	sc->sc_txbusy = 1;
 	/*
 	 * Setup the PDC to transfer the data and interrupt us when it
 	 * is done.  We've already requested the interrupt.
 	 */
-	WR4(&sc->sc_bas, PDC_TPR, addr);
+	WR4(&sc->sc_bas, PDC_TPR, atsc->tx_paddr);
 	WR4(&sc->sc_bas, PDC_TCR, sc->sc_txdatasz);
 	WR4(&sc->sc_bas, PDC_PTCR, PDC_PTCR_TXTEN);
 	WR4(&sc->sc_bas, USART_IER, USART_CSR_ENDTX);
-errout:
 	uart_unlock(sc->sc_hwmtx);
 	return (err);
 }
@@ -666,7 +663,6 @@ at91_usart_bus_ipend(struct uart_softc *sc)
 	if (csr & USART_CSR_ENDTX) {
 		bus_dmamap_sync(atsc->tx_tag, atsc->tx_map,
 		    BUS_DMASYNC_POSTWRITE);
-		bus_dmamap_unload(atsc->tx_tag, atsc->tx_map);
 	}
 	if (csr & (USART_CSR_TXRDY | USART_CSR_ENDTX)) {
 		if (sc->sc_txbusy)

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