[src/trunk]: src/sys/dev/spi ssdfb_spi: fix issues with command xfers needed ...

[tnn <tnn%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/747cf717b5a4
branches:  trunk
changeset: 1023007:747cf717b5a4
user:      tnn <tnn%NetBSD.org@localhost>
date:      Thu Aug 19 11:04:21 2021 +0000

description:
ssdfb_spi: fix issues with command xfers needed for SSD1306 & SH1106

These controllers require D/C# to be deasserted for the entire duration
of the command, contrary to docs and how newer controllers like SSD1353
behave. Probably this is needed for all controllers that do not have the
WRITE_RAM (0x5c) command. Also support using alternate padding commands
for 3-wire mode when WRITE_RAM is not available.

diffstat:

 sys/dev/spi/ssdfb_spi.c |  23 ++++++++++++-----------
 1 files changed, 12 insertions(+), 11 deletions(-)

diffs (94 lines):

diff -r 66a37b5f7e41 -r 747cf717b5a4 sys/dev/spi/ssdfb_spi.c
--- a/sys/dev/spi/ssdfb_spi.c   Thu Aug 19 11:03:04 2021 +0000
+++ b/sys/dev/spi/ssdfb_spi.c   Thu Aug 19 11:04:21 2021 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: ssdfb_spi.c,v 1.9 2021/08/05 19:17:22 tnn Exp $ */
+/* $NetBSD: ssdfb_spi.c,v 1.10 2021/08/19 11:04:21 tnn Exp $ */
 
 /*
  * Copyright (c) 2019 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: ssdfb_spi.c,v 1.9 2021/08/05 19:17:22 tnn Exp $");
+__KERNEL_RCSID(0, "$NetBSD: ssdfb_spi.c,v 1.10 2021/08/19 11:04:21 tnn Exp $");
 
 #include <sys/param.h>
 #include <sys/device.h>
@@ -58,6 +58,8 @@
        struct fdtbus_gpio_pin  *sc_gpio_res;
 #endif
        bool                    sc_3wiremode;
+       bool                    sc_late_dc_deassert;
+       uint8_t                 sc_padding_cmd;
 };
 
 static int     ssdfb_spi_match(device_t, cfdata_t, void *);
@@ -78,7 +80,7 @@
 static void    ssdfb_bitstream_append_cmd(struct bs_state *, uint8_t);
 static void    ssdfb_bitstream_append_data(struct bs_state *, uint8_t *,
                    size_t);
-static void    ssdfb_bitstream_final(struct bs_state *);
+static void    ssdfb_bitstream_final(struct bs_state *, uint8_t);
 
 CFATTACH_DECL_NEW(ssdfb_spi, sizeof(struct ssdfb_spi_softc),
     ssdfb_spi_match, ssdfb_spi_attach, NULL, NULL);
@@ -167,6 +169,7 @@
                sc->sc.sc_transfer_rect = sc->sc_3wiremode
                    ? ssdfb_spi_xfer_rect_3wire_ssd1322
                    : ssdfb_spi_xfer_rect_4wire_ssd1322;
+               sc->sc_padding_cmd = SSD1322_CMD_WRITE_RAM;
                break;
        case SSDFB_PRODUCT_SSD1353_GENERIC:
        case SSDFB_PRODUCT_DEP_160128A_RGB:
@@ -200,7 +203,7 @@
        cmd++;
        len--;
        ssdfb_bitstream_append_data(&s, cmd, len);
-       ssdfb_bitstream_final(&s);
+       ssdfb_bitstream_final(&s, sc->sc_padding_cmd);
 
        return spi_send(sc->sc_sh, s.cur - s.base, bitstream);
 }
@@ -230,7 +233,7 @@
        ssdfb_bitstream_append_data(&s, &fromcol, 1);
        ssdfb_bitstream_append_data(&s, &tocol, 1);
        ssdfb_bitstream_append_cmd(&s, SSD1322_CMD_WRITE_RAM);
-       ssdfb_bitstream_final(&s);
+       ssdfb_bitstream_final(&s, sc->sc_padding_cmd);
        error = spi_send(sc->sc_sh, s.cur - s.base, bitstream);
        if (error)
                return error;
@@ -239,7 +242,7 @@
        for (row = fromrow; row <= torow; row++) {
                ssdfb_bitstream_init(&s, bitstream);
                ssdfb_bitstream_append_data(&s, p, rlen);
-               ssdfb_bitstream_final(&s);
+               ssdfb_bitstream_final(&s, sc->sc_padding_cmd);
                error = spi_send(sc->sc_sh, s.cur - s.base, bitstream);
                if (error)
                        return error;
@@ -290,11 +293,8 @@
 }
 
 static void
-ssdfb_bitstream_final(struct bs_state *s)
+ssdfb_bitstream_final(struct bs_state *s, uint8_t padding_cmd)
 {
-       uint8_t padding_cmd = SSD1322_CMD_WRITE_RAM;
-       /* padding_cmd = SSDFB_NOP_CMD; */
-
        while (s->mask != 0x80) {
                ssdfb_bitstream_append_cmd(s, padding_cmd);
        }
@@ -321,7 +321,8 @@
        if (error)
                return error;
        if (len > 1) {
-               ssdfb_spi_4wire_set_dc(sc, 1);
+               if (!sc->sc_late_dc_deassert)
+                       ssdfb_spi_4wire_set_dc(sc, 1);
                len--;
                cmd++;
                error = spi_send(sc->sc_sh, len, cmd);