Date: Thu, 11 Jun 2020 06:44:58 -0700 (PDT) From: "Rodney W. Grimes" <freebsd@gndrsh.dnsmgr.net> To: Oleksandr Tymoshenko <gonzo@freebsd.org> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r362029 - head/sys/dev/hdmi Message-ID: <202006111344.05BDiwc4060074@gndrsh.dnsmgr.net> In-Reply-To: <202006102138.05ALcZZV087863@repo.freebsd.org>
next in thread | previous in thread | raw e-mail | index | archive | help
> Author: gonzo > Date: Wed Jun 10 21:38:35 2020 > New Revision: 362029 > URL: https://svnweb.freebsd.org/changeset/base/362029 > > Log: > Fix reading EDID on TVs/monitors without E-DCC support > > Writing segment id to I2C device 0x30 only required if the segment is > non-zero. On the devices without E-DCC support writing to that address > fails and whole transaction then fails too. To avoid this do > not attempt write to the segment selection device unless required. > > MFC after: 2 weeks Is it possible that this bad write is what has caused me to corrupt the EDID of 3 monitors over the last year while using a Display Port to HDMI cable on them? > Modified: > head/sys/dev/hdmi/dwc_hdmi.c > > Modified: head/sys/dev/hdmi/dwc_hdmi.c > ============================================================================== > --- head/sys/dev/hdmi/dwc_hdmi.c Wed Jun 10 21:18:19 2020 (r362028) > +++ head/sys/dev/hdmi/dwc_hdmi.c Wed Jun 10 21:38:35 2020 (r362029) > @@ -658,6 +658,11 @@ hdmi_edid_read(struct dwc_hdmi_softc *sc, int block, u > int result; > uint8_t addr = block & 1 ? EDID_LENGTH : 0; > uint8_t segment = block >> 1; > + /* > + * Some devices do not support E-DDC so attempt > + * writing segment address only if it's neccessary > + */ > + unsigned char xfers = segment ? 3 : 2; > struct iic_msg msg[] = { > { I2C_DDC_SEGADDR, IIC_M_WR, 1, &segment }, > { I2C_DDC_ADDR, IIC_M_WR, 1, &addr }, > @@ -687,7 +692,7 @@ hdmi_edid_read(struct dwc_hdmi_softc *sc, int block, u > return (result); > } > > - result = iicbus_transfer(i2c_dev, msg, 3); > + result = iicbus_transfer(i2c_dev, &msg[3 - xfers], xfers); > iicbus_release_bus(i2c_dev, sc->sc_dev); > > if (result) { > -- Rod Grimes rgrimes@freebsd.org
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?202006111344.05BDiwc4060074>