From patchwork Fri Jul 14 01:37:56 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sebastian Reichel X-Patchwork-Id: 702981 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 88532C001DD for ; Fri, 14 Jul 2023 01:38:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234562AbjGNBiY (ORCPT ); Thu, 13 Jul 2023 21:38:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58740 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234105AbjGNBiO (ORCPT ); Thu, 13 Jul 2023 21:38:14 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5D3502D7B; Thu, 13 Jul 2023 18:38:08 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C63AA61BCD; Fri, 14 Jul 2023 01:38:07 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 10310C433BD; Fri, 14 Jul 2023 01:38:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1689298687; bh=j8pDswVHzIfTvdkT2nYVTXa5vw9xRuWvNmDrAubLjII=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qgSc69w/n1FeisakITDh5sh81dAr+Zd1OjhByLooZwPoD74XW6MeiRIhNj677pFwV I9QzcUuyIhpEdQnIJWpITrdhyoweEd+BcN5cOt2jjHUxU5EpFk2xEXkQR7CabAfKHz t2RJiZTWNoHL0O1/jhWng1RSnmobMFJd6P4oxcAVlSphPYmX6yPD+4j50u20HaL1WK uroClo3gganL6oYLw/ymAXOrozY6yVeokjoL4vHaMfvsextSqLLoUeYI/Rn3zrFHVL cqPtJgERraS/nUnp6V1XiiszwnNJGNuzALTYNo7Houq+JfzNDGGUFn5UB0Vr4VadAv IX8S+pqfQ/C8Q== Received: by mercury (Postfix, from userid 1000) id 0713910676FB; Fri, 14 Jul 2023 03:37:59 +0200 (CEST) From: Sebastian Reichel To: Sebastian Reichel Cc: Gerald Loacker , Michael Riesch , Miquel Raynal , Thierry Reding , Sam Ravnborg , David Airlie , Daniel Vetter , Rob Herring , Krzysztof Kozlowski , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org, Maxime Ripard Subject: [PATCH v3 19/19] drm/panel: sitronix-st7789v: Check display ID Date: Fri, 14 Jul 2023 03:37:56 +0200 Message-Id: <20230714013756.1546769-20-sre@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230714013756.1546769-1-sre@kernel.org> References: <20230714013756.1546769-1-sre@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org From: Miquel Raynal A very basic debugging rule when a device is connected for the first time is to access a read-only register which contains known data in order to ensure the communication protocol is properly working. This driver lacked any read helper which is often a critical piece for speeding-up bring-ups. Add a read helper and use it to verify the communication with the panel is working as soon as possible in order to inform the user early if this is not the case. As this panel may work with no MISO line, the check is discarded in this case. Upon error, we do not fail probing but just warn the user, in case the DT description would be lacking the Rx bus width (which is likely on old descriptions) in order to avoid breaking existing devices. Signed-off-by: Miquel Raynal Acked-by: Sam Ravnborg Acked-by: Maxime Ripard Reviewed-by: Sebastian Reichel Tested-by: Sebastian Reichel # no MISO line Signed-off-by: Sebastian Reichel --- .../gpu/drm/panel/panel-sitronix-st7789v.c | 81 +++++++++++++++++++ 1 file changed, 81 insertions(+) diff --git a/drivers/gpu/drm/panel/panel-sitronix-st7789v.c b/drivers/gpu/drm/panel/panel-sitronix-st7789v.c index 47387f127e05..dc010d87a9ef 100644 --- a/drivers/gpu/drm/panel/panel-sitronix-st7789v.c +++ b/drivers/gpu/drm/panel/panel-sitronix-st7789v.c @@ -110,6 +110,9 @@ return val; \ } while (0) +#define ST7789V_IDS { 0x85, 0x85, 0x52 } +#define ST7789V_IDS_SIZE 3 + struct st7789_panel_info { const struct drm_display_mode *mode; u32 bus_format; @@ -157,6 +160,76 @@ static int st7789v_write_data(struct st7789v *ctx, u8 cmd) return st7789v_spi_write(ctx, ST7789V_DATA, cmd); } +static int st7789v_read_data(struct st7789v *ctx, u8 cmd, u8 *buf, + unsigned int len) +{ + struct spi_transfer xfer[2] = { }; + struct spi_message msg; + u16 txbuf = ((ST7789V_COMMAND & 1) << 8) | cmd; + u16 rxbuf[4] = {}; + u8 bit9 = 0; + int ret, i; + + switch (len) { + case 1: + case 3: + case 4: + break; + default: + return -EOPNOTSUPP; + } + + spi_message_init(&msg); + + xfer[0].tx_buf = &txbuf; + xfer[0].len = sizeof(txbuf); + spi_message_add_tail(&xfer[0], &msg); + + xfer[1].rx_buf = rxbuf; + xfer[1].len = len * 2; + spi_message_add_tail(&xfer[1], &msg); + + ret = spi_sync(ctx->spi, &msg); + if (ret) + return ret; + + for (i = 0; i < len; i++) { + buf[i] = rxbuf[i] >> i | (bit9 << (9 - i)); + if (i) + bit9 = rxbuf[i] & GENMASK(i - 1, 0); + } + + return 0; +} + +static int st7789v_check_id(struct drm_panel *panel) +{ + const u8 st7789v_ids[ST7789V_IDS_SIZE] = ST7789V_IDS; + struct st7789v *ctx = panel_to_st7789v(panel); + bool invalid_ids = false; + int ret, i; + u8 ids[3]; + + if (ctx->spi->mode & SPI_NO_RX) + return 0; + + ret = st7789v_read_data(ctx, MIPI_DCS_GET_DISPLAY_ID, ids, ST7789V_IDS_SIZE); + if (ret) + return ret; + + for (i = 0; i < ST7789V_IDS_SIZE; i++) { + if (ids[i] != st7789v_ids[i]) { + invalid_ids = true; + break; + } + } + + if (invalid_ids) + return -EIO; + + return 0; +} + static const struct drm_display_mode default_mode = { .clock = 7000, .hdisplay = 240, @@ -295,6 +368,14 @@ static int st7789v_prepare(struct drm_panel *panel) gpiod_set_value(ctx->reset, 0); msleep(120); + /* + * Avoid failing if the IDs are invalid in case the Rx bus width + * description is missing. + */ + ret = st7789v_check_id(panel); + if (ret) + dev_warn(panel->dev, "Unrecognized panel IDs"); + ST7789V_TEST(ret, st7789v_write_command(ctx, MIPI_DCS_EXIT_SLEEP_MODE)); /* We need to wait 120ms after a sleep out command */